diff --git a/azurerm/helpers/validate/network.go b/azurerm/helpers/validate/network.go
index 390d5721f679..609a23a33ae3 100644
--- a/azurerm/helpers/validate/network.go
+++ b/azurerm/helpers/validate/network.go
@@ -47,14 +47,26 @@ func MACAddress(i interface{}, k string) (_ []string, errors []error) {
 }
 
 func PortNumber(i interface{}, k string) (_ []string, errors []error) {
+	return validatePortNumber(i, k, false)
+}
+
+func PortNumberOrZero(i interface{}, k string) (_ []string, errors []error) {
+	return validatePortNumber(i, k, true)
+}
+
+func validatePortNumber(i interface{}, k string, allowZero bool) (_ []string, errors []error) {
 	v, ok := i.(int)
 	if !ok {
 		errors = append(errors, fmt.Errorf("expected type of %q to be int", k))
 		return
 	}
 
+	if allowZero && v == 0 {
+		return
+	}
+
 	if v < 1 || 65535 < v {
-		errors = append(errors, fmt.Errorf("%q is not a valid port number: %q", k, i))
+		errors = append(errors, fmt.Errorf("%q is not a valid port number: %d", k, v))
 	}
 
 	return
diff --git a/azurerm/helpers/validate/network_test.go b/azurerm/helpers/validate/network_test.go
index b2e91fdd7bb5..3911319b0b77 100644
--- a/azurerm/helpers/validate/network_test.go
+++ b/azurerm/helpers/validate/network_test.go
@@ -196,3 +196,49 @@ func TestPortNumber(t *testing.T) {
 		})
 	}
 }
+
+func TestPortNumberOrZero(t *testing.T) {
+	cases := []struct {
+		Port   int
+		Errors int
+	}{
+		{
+			Port:   -1,
+			Errors: 1,
+		},
+		{
+			Port:   0,
+			Errors: 0,
+		},
+		{
+			Port:   1,
+			Errors: 0,
+		},
+		{
+			Port:   8477,
+			Errors: 0,
+		},
+		{
+			Port:   65535,
+			Errors: 0,
+		},
+		{
+			Port:   65536,
+			Errors: 1,
+		},
+		{
+			Port:   7000000,
+			Errors: 1,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(strconv.Itoa(tc.Port), func(t *testing.T) {
+			_, errors := PortNumberOrZero(tc.Port, "test")
+
+			if len(errors) != tc.Errors {
+				t.Fatalf("Expected PortNumberOrZero to return %d error(s) not %d", len(errors), tc.Errors)
+			}
+		})
+	}
+}
diff --git a/azurerm/resource_arm_loadbalancer_rule.go b/azurerm/resource_arm_loadbalancer_rule.go
index 44ca3c0b3322..7142156cfad5 100644
--- a/azurerm/resource_arm_loadbalancer_rule.go
+++ b/azurerm/resource_arm_loadbalancer_rule.go
@@ -78,13 +78,13 @@ func resourceArmLoadBalancerRule() *schema.Resource {
 			"frontend_port": {
 				Type:         schema.TypeInt,
 				Required:     true,
-				ValidateFunc: validate.PortNumber,
+				ValidateFunc: validate.PortNumberOrZero,
 			},
 
 			"backend_port": {
 				Type:         schema.TypeInt,
 				Required:     true,
-				ValidateFunc: validate.PortNumber,
+				ValidateFunc: validate.PortNumberOrZero,
 			},
 
 			"probe_id": {
diff --git a/website/docs/r/loadbalancer_rule.html.markdown b/website/docs/r/loadbalancer_rule.html.markdown
index 5f0ef7980af5..a9e013fee428 100644
--- a/website/docs/r/loadbalancer_rule.html.markdown
+++ b/website/docs/r/loadbalancer_rule.html.markdown
@@ -58,8 +58,8 @@ The following arguments are supported:
 * `loadbalancer_id` - (Required) The ID of the Load Balancer in which to create the Rule.
 * `frontend_ip_configuration_name` - (Required) The name of the frontend IP configuration to which the rule is associated.
 * `protocol` - (Required) The transport protocol for the external endpoint. Possible values are `Tcp`, `Udp` or `All`.
-* `frontend_port` - (Required) The port for the external endpoint. Port numbers for each Rule must be unique within the Load Balancer. Possible values range between 1 and 65534, inclusive.
-* `backend_port` - (Required) The port used for internal connections on the endpoint. Possible values range between 1 and 65535, inclusive.
+* `frontend_port` - (Required) The port for the external endpoint. Port numbers for each Rule must be unique within the Load Balancer. Possible values range between 0 and 65534, inclusive.
+* `backend_port` - (Required) The port used for internal connections on the endpoint. Possible values range between 0 and 65535, inclusive.
 * `backend_address_pool_id` - (Optional) A reference to a Backend Address Pool over which this Load Balancing Rule operates.
 * `probe_id` - (Optional) A reference to a Probe used by this Load Balancing Rule.
 * `enable_floating_ip` - (Optional) Floating IP is pertinent to failover scenarios: a "floating” IP is reassigned to a secondary server in case the primary server fails. Floating IP is required for SQL AlwaysOn.