diff --git a/internal/puzzles/solutions/2016/day03/solution.go b/internal/puzzles/solutions/2016/day03/solution.go
new file mode 100644
index 00000000..cb6a0d9b
--- /dev/null
+++ b/internal/puzzles/solutions/2016/day03/solution.go
@@ -0,0 +1,30 @@
+// Package day03 contains solution for https://adventofcode.com/2016/day/3 puzzle.
+package day03
+
+import (
+	"io"
+
+	"github.com/obalunenko/advent-of-code/internal/puzzles"
+)
+
+func init() {
+	puzzles.Register(solution{})
+}
+
+type solution struct{}
+
+func (s solution) Year() string {
+	return puzzles.Year2016.String()
+}
+
+func (s solution) Day() string {
+	return puzzles.Day03.String()
+}
+
+func (s solution) Part1(input io.Reader) (string, error) {
+	return "", puzzles.ErrNotImplemented
+}
+
+func (s solution) Part2(input io.Reader) (string, error) {
+	return "", puzzles.ErrNotImplemented
+}
diff --git a/internal/puzzles/solutions/2016/day03/solution_test.go b/internal/puzzles/solutions/2016/day03/solution_test.go
new file mode 100644
index 00000000..0d9b6ef7
--- /dev/null
+++ b/internal/puzzles/solutions/2016/day03/solution_test.go
@@ -0,0 +1,123 @@
+package day03
+
+import (
+	"errors"
+	"io"
+	"strings"
+	"testing"
+	"testing/iotest"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_solution_Year(t *testing.T) {
+	var s solution
+
+	want := "2016"
+	got := s.Year()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Day(t *testing.T) {
+	var s solution
+
+	want := "3"
+	got := s.Day()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Part1(t *testing.T) {
+	var s solution
+
+	type args struct {
+		input io.Reader
+	}
+
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr assert.ErrorAssertionFunc
+	}{
+		{
+			name: "test example from description",
+			args: args{
+				input: strings.NewReader("5 10 25\n"),
+			},
+			want:    "0",
+			wantErr: assert.NoError,
+		},
+		{
+			name: "test example from description",
+			args: args{
+				input: strings.NewReader("5 10 7\n"),
+			},
+			want:    "1",
+			wantErr: assert.NoError,
+		},
+		{
+			name: "",
+			args: args{
+				input: iotest.ErrReader(errors.New("custom error")),
+			},
+			want:    "",
+			wantErr: assert.Error,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := s.Part1(tt.args.input)
+			if !tt.wantErr(t, err) {
+				return
+			}
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func Test_solution_Part2(t *testing.T) {
+	var s solution
+
+	type args struct {
+		input io.Reader
+	}
+
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr assert.ErrorAssertionFunc
+	}{
+		{
+			name: "test example from description",
+			args: args{
+				input: strings.NewReader(""),
+			},
+			want:    "230",
+			wantErr: assert.NoError,
+		},
+		{
+			name: "",
+			args: args{
+				input: iotest.ErrReader(errors.New("custom error")),
+			},
+			want:    "",
+			wantErr: assert.Error,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := s.Part2(tt.args.input)
+			if !tt.wantErr(t, err) {
+				return
+			}
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
diff --git a/internal/puzzles/solutions/2016/day03/spec.md b/internal/puzzles/solutions/2016/day03/spec.md
new file mode 100644
index 00000000..779022a4
--- /dev/null
+++ b/internal/puzzles/solutions/2016/day03/spec.md
@@ -0,0 +1,18 @@
+# --- Day 3: Squares With Three Sides ---
+
+## --- Part One ---
+
+Now that you can think clearly, you move deeper into the labyrinth of hallways and office furniture that makes up this 
+part of Easter Bunny HQ. This must be a graphic design department; the walls are covered in specifications for 
+triangles.
+
+Or are they?
+
+The design document gives the side lengths of each triangle it describes, but... `5 10 25`? 
+Some of these aren't triangles. You can't help but mark the impossible ones.
+
+In a valid triangle, the sum of any two sides must be larger than the remaining side. 
+
+For example, the "triangle" given above is impossible, because `5 + 10` is not larger than `25`.
+
+In your puzzle input, how many of the listed triangles are possible?
\ No newline at end of file
diff --git a/internal/puzzles/solutions/register_2016.go b/internal/puzzles/solutions/register_2016.go
index 702bca8e..ec2b59c4 100644
--- a/internal/puzzles/solutions/register_2016.go
+++ b/internal/puzzles/solutions/register_2016.go
@@ -8,4 +8,6 @@ import (
 	_ "github.com/obalunenko/advent-of-code/internal/puzzles/solutions/2016/day01"
 	// register day02 solution.
 	_ "github.com/obalunenko/advent-of-code/internal/puzzles/solutions/2016/day02"
+	// register day03 solution.
+	_ "github.com/obalunenko/advent-of-code/internal/puzzles/solutions/2016/day03"
 )