diff --git a/NEWS.md b/NEWS.md
index 998a191a16767..baa5f0ee72e17 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -66,6 +66,8 @@ Deprecated or removed
 
   * `is` has been deprecated in favor of `===` (which used to be an alias for `is`) ([#17758]).
 
+  * `num` and `den` have been deprecated in favor of `numerator` and `denominator` respectively ([#19233]).
+
 Julia v0.5.0 Release Notes
 ==========================
 
@@ -693,3 +695,4 @@ Language tooling improvements
 [#18473]: https://github.com/JuliaLang/julia/issues/18473
 [#18839]: https://github.com/JuliaLang/julia/issues/18839
 [#19018]: https://github.com/JuliaLang/julia/issues/19018
+[#19233]: https://github.com/JuliaLang/julia/issues/19233
diff --git a/base/deprecated.jl b/base/deprecated.jl
index b99709c5f8021..61d44915cd287 100644
--- a/base/deprecated.jl
+++ b/base/deprecated.jl
@@ -1087,4 +1087,8 @@ eval(Base.LinAlg, quote
     end
 end)
 
+# #19246
+@deprecate den denominator
+@deprecate num numerator
+
 # End deprecations scheduled for 0.6
diff --git a/base/docs/helpdb/Base.jl b/base/docs/helpdb/Base.jl
index 2b75cedb08b38..aa9cb83ba5630 100644
--- a/base/docs/helpdb/Base.jl
+++ b/base/docs/helpdb/Base.jl
@@ -999,13 +999,6 @@ In-place version of [`reverse`](:func:`reverse`).
 """
 reverse!
 
-"""
-    num(x)
-
-Numerator of the rational representation of `x`.
-"""
-num
-
 """
     .<(x, y)
 
@@ -2617,13 +2610,6 @@ The process was stopped by a terminal interrupt (CTRL+C).
 """
 InterruptException
 
-"""
-    den(x)
-
-Denominator of the rational representation of `x`.
-"""
-den
-
 """
     issubnormal(f) -> Bool
 
diff --git a/base/exports.jl b/base/exports.jl
index 6cdaf50c3bf3c..5b7757236ef9a 100644
--- a/base/exports.jl
+++ b/base/exports.jl
@@ -332,7 +332,7 @@ export
     csch,
     dawson,
     deg2rad,
-    den,
+    denominator,
     digamma,
     div,
     divrem,
@@ -400,7 +400,7 @@ export
     nextpow,
     nextpow2,
     nextprod,
-    num,
+    numerator,
     num2hex,
     one,
     powermod,
diff --git a/base/hashing2.jl b/base/hashing2.jl
index 3d29fcef204c5..403c5a62e1e93 100644
--- a/base/hashing2.jl
+++ b/base/hashing2.jl
@@ -94,7 +94,7 @@ Special values:
 =#
 
 decompose(x::Integer) = x, 0, 1
-decompose(x::Rational) = num(x), 0, den(x)
+decompose(x::Rational) = numerator(x), 0, denominator(x)
 
 function decompose(x::Float16)::NTuple{3,Int}
     isnan(x) && return 0, 0, 0
@@ -144,7 +144,7 @@ end
 ## streamlined hashing for smallish rational types ##
 
 function hash{T<:BitInteger64}(x::Rational{T}, h::UInt)
-    num, den = Base.num(x), Base.den(x)
+    num, den = Base.numerator(x), Base.denominator(x)
     den == 1 && return hash(num, h)
     den == 0 && return hash(ifelse(num > 0, Inf, -Inf), h)
     if isodd(den)
diff --git a/base/mpfr.jl b/base/mpfr.jl
index 25c92fa3c6ee8..1ac8dadb57d3b 100644
--- a/base/mpfr.jl
+++ b/base/mpfr.jl
@@ -107,7 +107,7 @@ convert(::Type{BigFloat}, x::Union{Bool,Int8,Int16,Int32}) = BigFloat(convert(Cl
 convert(::Type{BigFloat}, x::Union{UInt8,UInt16,UInt32}) = BigFloat(convert(Culong,x))
 
 convert(::Type{BigFloat}, x::Union{Float16,Float32}) = BigFloat(Float64(x))
-convert(::Type{BigFloat}, x::Rational) = BigFloat(num(x)) / BigFloat(den(x))
+convert(::Type{BigFloat}, x::Rational) = BigFloat(numerator(x)) / BigFloat(denominator(x))
 
 function tryparse(::Type{BigFloat}, s::AbstractString, base::Int=0)
     z = BigFloat()
diff --git a/base/rational.jl b/base/rational.jl
index e3d7bb4911e98..f65397c064788 100644
--- a/base/rational.jl
+++ b/base/rational.jl
@@ -44,9 +44,9 @@ end
 .//(y::Number, X::AbstractArray) = reshape([ y // x for x in X ], size(X))
 
 function show(io::IO, x::Rational)
-    show(io, num(x))
+    show(io, numerator(x))
     print(io, "//")
-    show(io, den(x))
+    show(io, denominator(x))
 end
 
 function read{T<:Integer}(s::IO, ::Type{Rational{T}})
@@ -55,7 +55,7 @@ function read{T<:Integer}(s::IO, ::Type{Rational{T}})
     r//i
 end
 function write(s::IO, z::Rational)
-    write(s,num(z),den(z))
+    write(s,numerator(z),denominator(z))
 end
 
 convert{T<:Integer}(::Type{Rational{T}}, x::Rational) = Rational{T}(convert(T,x.num),convert(T,x.den))
@@ -104,7 +104,7 @@ julia> rationalize(5.6)
 julia> a = rationalize(BigInt, 10.3)
 103//10
 
-julia> typeof(num(a))
+julia> typeof(numerator(a))
 BigInt
 ```
 """
@@ -170,10 +170,21 @@ end
 rationalize{T<:Integer}(::Type{T}, x::AbstractFloat; tol::Real=eps(x)) = rationalize(T, x, tol)::Rational{T}
 rationalize(x::AbstractFloat; kvs...) = rationalize(Int, x; kvs...)
 
-num(x::Integer) = x
-den(x::Integer) = one(x)
-num(x::Rational) = x.num
-den(x::Rational) = x.den
+"""
+    numerator(x)
+
+Numerator of the rational representation of `x`.
+"""
+numerator(x::Integer) = x
+numerator(x::Rational) = x.num
+
+"""
+    denominator(x)
+
+Denominator of the rational representation of `x`.
+"""
+denominator(x::Integer) = one(x)
+denominator(x::Rational) = x.den
 
 sign(x::Rational) = oftype(x, sign(x.num))
 signbit(x::Rational) = signbit(x.num)
@@ -313,15 +324,15 @@ ceil{ T}(::Type{T}, x::Rational) = convert(T,cld(x.num,x.den))
 
 
 function round{T, Tr}(::Type{T}, x::Rational{Tr}, ::RoundingMode{:Nearest})
-    if den(x) == zero(Tr) && T <: Integer
+    if denominator(x) == zero(Tr) && T <: Integer
         throw(DivideError())
-    elseif den(x) == zero(Tr)
-        return convert(T, copysign(one(Tr)//zero(Tr), num(x)))
+    elseif denominator(x) == zero(Tr)
+        return convert(T, copysign(one(Tr)//zero(Tr), numerator(x)))
     end
-    q,r = divrem(num(x), den(x))
+    q,r = divrem(numerator(x), denominator(x))
     s = q
-    if abs(r) >= abs((den(x)-copysign(Tr(4), num(x))+one(Tr)+iseven(q))>>1 + copysign(Tr(2), num(x)))
-        s += copysign(one(Tr),num(x))
+    if abs(r) >= abs((denominator(x)-copysign(Tr(4), numerator(x))+one(Tr)+iseven(q))>>1 + copysign(Tr(2), numerator(x)))
+        s += copysign(one(Tr),numerator(x))
     end
     convert(T, s)
 end
@@ -329,35 +340,35 @@ end
 round{T}(::Type{T}, x::Rational) = round(T, x, RoundNearest)
 
 function round{T, Tr}(::Type{T}, x::Rational{Tr}, ::RoundingMode{:NearestTiesAway})
-    if den(x) == zero(Tr) && T <: Integer
+    if denominator(x) == zero(Tr) && T <: Integer
         throw(DivideError())
-    elseif den(x) == zero(Tr)
-        return convert(T, copysign(one(Tr)//zero(Tr), num(x)))
+    elseif denominator(x) == zero(Tr)
+        return convert(T, copysign(one(Tr)//zero(Tr), numerator(x)))
     end
-    q,r = divrem(num(x), den(x))
+    q,r = divrem(numerator(x), denominator(x))
     s = q
-    if abs(r) >= abs((den(x)-copysign(Tr(4), num(x))+one(Tr))>>1 + copysign(Tr(2), num(x)))
-        s += copysign(one(Tr),num(x))
+    if abs(r) >= abs((denominator(x)-copysign(Tr(4), numerator(x))+one(Tr))>>1 + copysign(Tr(2), numerator(x)))
+        s += copysign(one(Tr),numerator(x))
     end
     convert(T, s)
 end
 
 function round{T, Tr}(::Type{T}, x::Rational{Tr}, ::RoundingMode{:NearestTiesUp})
-    if den(x) == zero(Tr) && T <: Integer
+    if denominator(x) == zero(Tr) && T <: Integer
         throw(DivideError())
-    elseif den(x) == zero(Tr)
-        return convert(T, copysign(one(Tr)//zero(Tr), num(x)))
+    elseif denominator(x) == zero(Tr)
+        return convert(T, copysign(one(Tr)//zero(Tr), numerator(x)))
     end
-    q,r = divrem(num(x), den(x))
+    q,r = divrem(numerator(x), denominator(x))
     s = q
-    if abs(r) >= abs((den(x)-copysign(Tr(4), num(x))+one(Tr)+(num(x)<0))>>1 + copysign(Tr(2), num(x)))
-        s += copysign(one(Tr),num(x))
+    if abs(r) >= abs((denominator(x)-copysign(Tr(4), numerator(x))+one(Tr)+(numerator(x)<0))>>1 + copysign(Tr(2), numerator(x)))
+        s += copysign(one(Tr),numerator(x))
     end
     convert(T, s)
 end
 
 function round{T}(::Type{T}, x::Rational{Bool})
-    if den(x) == false && issubtype(T, Union{Integer, Bool})
+    if denominator(x) == false && issubtype(T, Union{Integer, Bool})
         throw(DivideError())
     end
     convert(T, x)
diff --git a/base/sysimg.jl b/base/sysimg.jl
index 82b4d45cc0a90..8e5dd922b6594 100644
--- a/base/sysimg.jl
+++ b/base/sysimg.jl
@@ -247,7 +247,7 @@ include("mpfr.jl")
 importall .MPFR
 big(n::Integer) = convert(BigInt,n)
 big(x::AbstractFloat) = convert(BigFloat,x)
-big(q::Rational) = big(num(q))//big(den(q))
+big(q::Rational) = big(numerator(q))//big(denominator(q))
 
 include("combinatorics.jl")
 
diff --git a/doc/manual/complex-and-rational-numbers.rst b/doc/manual/complex-and-rational-numbers.rst
index c23b5bdd53277..c0da0998bb1f7 100644
--- a/doc/manual/complex-and-rational-numbers.rst
+++ b/doc/manual/complex-and-rational-numbers.rst
@@ -229,14 +229,14 @@ are reduced to lowest terms such that the denominator is non-negative:
 This normalized form for a ratio of integers is unique, so equality of
 rational values can be tested by checking for equality of the numerator
 and denominator. The standardized numerator and denominator of a
-rational value can be extracted using the :func:`num` and :func:`den` functions:
+rational value can be extracted using the :func:`numerator` and :func:`denominator` functions:
 
 .. doctest::
 
-    julia> num(2//3)
+    julia> numerator(2//3)
     2
 
-    julia> den(2//3)
+    julia> denominator(2//3)
     3
 
 Direct comparison of the numerator and denominator is generally not
diff --git a/doc/stdlib/math.rst b/doc/stdlib/math.rst
index e034c02b2726a..148965f19374d 100644
--- a/doc/stdlib/math.rst
+++ b/doc/stdlib/math.rst
@@ -324,13 +324,13 @@ Mathematical Operators
        julia> typeof(num(a))
        BigInt
 
-.. function:: num(x)
+.. function:: numerator(x)
 
    .. Docstring generated from Julia source
 
    Numerator of the rational representation of ``x``\ .
 
-.. function:: den(x)
+.. function:: denominator(x)
 
    .. Docstring generated from Julia source
 
diff --git a/test/hashing.jl b/test/hashing.jl
index 272c20a1d6172..60da16201cfe9 100644
--- a/test/hashing.jl
+++ b/test/hashing.jl
@@ -20,7 +20,7 @@ vals = vcat(
 
 function coerce(T::Type, x)
     if T<:Rational
-        convert(T, coerce(typeof(num(zero(T))), x))
+        convert(T, coerce(typeof(numerator(zero(T))), x))
     elseif !(T<:Integer)
         convert(T, x)
     else
diff --git a/test/numbers.jl b/test/numbers.jl
index d08c6b7a3ba97..cb28f874c7793 100644
--- a/test/numbers.jl
+++ b/test/numbers.jl
@@ -1299,9 +1299,9 @@ for yr = Any[
         f2, m2 = fldmod(x,y)
 
         t1 = isa(x,Rational) && isa(y,Rational) ?
-                               promote_type(typeof(num(x)),typeof(num(y))) :
-             isa(x,Rational) ? promote_type(typeof(num(x)),typeof(y)) :
-             isa(y,Rational) ? promote_type(typeof(x),typeof(num(y))) :
+                               promote_type(typeof(numerator(x)),typeof(numerator(y))) :
+             isa(x,Rational) ? promote_type(typeof(numerator(x)),typeof(y)) :
+             isa(y,Rational) ? promote_type(typeof(x),typeof(numerator(y))) :
                                promote_type(typeof(x),typeof(y))
 
         t2 = promote_type(typeof(x),typeof(y))
@@ -2630,8 +2630,8 @@ end
 rand_int = rand(Int8)
 
 for T in [Int8, Int16, Int32, Int128, BigInt]
-    @test num(convert(T, rand_int)) == rand_int
-    @test den(convert(T, rand_int)) == 1
+    @test numerator(convert(T, rand_int)) == rand_int
+    @test denominator(convert(T, rand_int)) == 1
 
     @test typemin(Rational{T}) == -one(T)//zero(T)
     @test typemax(Rational{T}) == one(T)//zero(T)