diff --git a/packages/babel-generator/src/generators/flow.js b/packages/babel-generator/src/generators/flow.js
index d886840e27..15f39923ca 100644
--- a/packages/babel-generator/src/generators/flow.js
+++ b/packages/babel-generator/src/generators/flow.js
@@ -187,6 +187,27 @@ export function TypeAnnotation(node: Object) {
   this.print(node.typeAnnotation, node);
 }
 
+export function TypeParameter(node: Object) {
+  if (node.variance === "plus") {
+    this.push("+");
+  } else if (node.variance === "minus") {
+    this.push("-");
+  }
+
+  this.push(node.name);
+
+  if (node.bound) {
+    this.print(node.bound, node);
+  }
+
+  if (node.default) {
+    this.space();
+    this.push("=");
+    this.space();
+    this.print(node.default, node);
+  }
+}
+
 export function TypeParameterInstantiation(node: Object) {
   this.push("<");
   this.printJoin(node.params, node, {
diff --git a/packages/babel-generator/src/generators/types.js b/packages/babel-generator/src/generators/types.js
index 6ca86a74e1..5eb8e1148d 100644
--- a/packages/babel-generator/src/generators/types.js
+++ b/packages/babel-generator/src/generators/types.js
@@ -8,10 +8,12 @@ export function Identifier(node: Object) {
   // This is a terrible hack, but changing type annotations to use a new,
   // dedicated node would be a breaking change. This should be cleaned up in
   // the next major.
-  if (node.variance === "plus") {
-    this.push("+");
-  } else if (node.variance === "minus") {
-    this.push("-");
+  if (node.variance) {
+    if (node.variance === "plus") {
+      this.push("+");
+    } else if (node.variance === "minus") {
+      this.push("-");
+    }
   }
 
   this.push(node.name);
diff --git a/packages/babel-generator/test/fixtures/flow/type-parameters/actual.js b/packages/babel-generator/test/fixtures/flow/type-parameters/actual.js
new file mode 100644
index 0000000000..8c307485e8
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/flow/type-parameters/actual.js
@@ -0,0 +1,21 @@
+type A<T = string> = T;
+type A<T = *> = T;
+type A<T: ?string = string> = T;
+type A<S, T: ?string = string> = T;
+type A<S = number, T: ?string = string> = T;
+class A<T = string> {};
+class A<T: ?string = string> {};
+class A<S, T: ?string = string> {};
+class A<S = number, T: ?string = string> {};
+(class A<T = string> {});
+(class A<T: ?string = string> {});
+(class A<S, T: ?string = string> {});
+(class A<S = number, T: ?string = string> {});
+declare class A<T = string> {};
+declare class A<T: ?string = string> {};
+declare class A<S, T: ?string = string> {};
+declare class A<S = number, T: ?string = string> {};
+interface A<T = string> {};
+interface A<T: ?string = string> {};
+interface A<S, T: ?string = string> {};
+interface A<S = number, T: ?string = string> {};
diff --git a/packages/babel-generator/test/fixtures/flow/type-parameters/expected.js b/packages/babel-generator/test/fixtures/flow/type-parameters/expected.js
new file mode 100644
index 0000000000..8c307485e8
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/flow/type-parameters/expected.js
@@ -0,0 +1,21 @@
+type A<T = string> = T;
+type A<T = *> = T;
+type A<T: ?string = string> = T;
+type A<S, T: ?string = string> = T;
+type A<S = number, T: ?string = string> = T;
+class A<T = string> {};
+class A<T: ?string = string> {};
+class A<S, T: ?string = string> {};
+class A<S = number, T: ?string = string> {};
+(class A<T = string> {});
+(class A<T: ?string = string> {});
+(class A<S, T: ?string = string> {});
+(class A<S = number, T: ?string = string> {});
+declare class A<T = string> {};
+declare class A<T: ?string = string> {};
+declare class A<S, T: ?string = string> {};
+declare class A<S = number, T: ?string = string> {};
+interface A<T = string> {};
+interface A<T: ?string = string> {};
+interface A<S, T: ?string = string> {};
+interface A<S = number, T: ?string = string> {};
diff --git a/packages/babel-types/src/definitions/flow.js b/packages/babel-types/src/definitions/flow.js
index d01da22505..95f9b40077 100644
--- a/packages/babel-types/src/definitions/flow.js
+++ b/packages/babel-types/src/definitions/flow.js
@@ -233,6 +233,14 @@ defineType("TypeCastExpression", {
   }
 });
 
+defineType("TypeParameter", {
+  visitor: ["name", "bound"],
+  aliases: ["Flow"],
+  fields: {
+    // todo
+  }
+});
+
 defineType("TypeParameterDeclaration", {
   visitor: ["params"],
   aliases: ["Flow"],