diff --git a/src/collector/declarations.js b/src/collector/declarations.js
index df22ccc..ad1af0d 100644
--- a/src/collector/declarations.js
+++ b/src/collector/declarations.js
@@ -166,8 +166,8 @@ function extractCommonjsNamedExternals<+T: Node>(nodes: T[], path: string): Exte
 
 function processExportNamedDeclaration(ctx: Context, node: ExportNamedDeclaration) {
     if (isDeclaration(node.declaration)) {
+        node.declaration.leadingComments = node.leadingComments;
         const reference = processDeclaration(ctx, node.declaration);
-
         ctx.provide(reference, reference);
     }
 
diff --git a/src/collector/definitions.js b/src/collector/definitions.js
index 7fb1b6c..6916182 100644
--- a/src/collector/definitions.js
+++ b/src/collector/definitions.js
@@ -4,7 +4,7 @@ import wu from 'wu';
 
 // @see flow#5376.
 import type {
-    ArrayTypeAnnotation, ClassDeclaration, ClassProperty, Comment, FlowTypeAnnotation,
+    Node, ArrayTypeAnnotation, ClassDeclaration, ClassProperty, Comment, FlowTypeAnnotation,
     GenericTypeAnnotation, InterfaceDeclaration, IntersectionTypeAnnotation, TypeAlias,
     UnionTypeAnnotation, NullableTypeAnnotation, ObjectTypeIndexer, ObjectTypeProperty,
     StringLiteralTypeAnnotation, ObjectTypeAnnotation, AnyTypeAnnotation, MixedTypeAnnotation,
@@ -37,6 +37,7 @@ function processTypeAlias(ctx: Context, node: TypeAlias | DeclareTypeAlias) {
         ctx.define(name, t.createAny());
 
         const type = makeType(ctx, node.right);
+        addComment(node, type);
 
         // TODO: support function aliases.
         invariant(type);
@@ -45,6 +46,15 @@ function processTypeAlias(ctx: Context, node: TypeAlias | DeclareTypeAlias) {
     }
 }
 
+function addComment(node: Node, type: Type) {
+    if (node.leadingComments) {
+        const cmt = node.leadingComments.map(c => c.value).join('\n').trim();
+        if (cmt) {
+            type.comment = cmt;
+        }
+    }
+}
+
 // TODO: type params.
 function processInterfaceDeclaration(
     ctx: Context,
@@ -52,6 +62,7 @@ function processInterfaceDeclaration(
 ) {
     const {name} = node.id;
     const type = makeType(ctx, node.body);
+    addComment(node, type);
 
     invariant(type);
 
@@ -215,6 +226,7 @@ function makeField(ctx: Context, node: ObjectTypeProperty | ClassProperty): ?Fie
         invariant(value);
 
         type = makeType(ctx, value);
+        addComment(node, type);
     }
 
     if (!type) {
@@ -238,12 +250,14 @@ function makeField(ctx: Context, node: ObjectTypeProperty | ClassProperty): ?Fie
 function makeMap(ctx: Context, node: ObjectTypeIndexer): ?MapType {
     const keys = makeType(ctx, node.key);
     const values = makeType(ctx, node.value);
+    addComment(node, values);
 
     return keys && values ? t.createMap(keys, values) : null;
 }
 
 function makeArray(ctx: Context, node: ArrayTypeAnnotation): ?ArrayType {
     const items = makeType(ctx, node.elementType);
+    addComment(node, items);
 
     return items != null ? t.createArray(items) : null;
 }
diff --git a/src/generators/jsonSchema.js b/src/generators/jsonSchema.js
index 9b4ce9c..293ed66 100644
--- a/src/generators/jsonSchema.js
+++ b/src/generators/jsonSchema.js
@@ -12,6 +12,7 @@ export type Schema = boolean | {
     id?: string,
     $ref?: string,
     $schema?: string,
+    $comment?: string,
     title?: string,
     description?: string,
     default?: mixed,
@@ -45,6 +46,18 @@ export type Schema = boolean | {
 };
 
 function convert(fund: Fund, type: ?Type): Schema {
+    let schema = convertType(fund, type);
+    if (type && type.comment) {
+        if (schema === true) {
+            schema = { $comment: type.comment };
+        } else {
+            schema.$comment = type.comment;
+        }
+    }
+    return schema;
+}
+
+function convertType(fund: Fund, type: ?Type): Schema {
     if (!type) {
         return {
             type: 'null',
diff --git a/src/types.js b/src/types.js
index 34b75d4..51458a8 100644
--- a/src/types.js
+++ b/src/types.js
@@ -21,6 +21,7 @@ export type TypeId = string[];
 
 export type BaseType = {
     id?: TypeId,
+    comment?: string,
 };
 
 export type RecordType = BaseType & {