diff --git a/src/js.rs b/src/js.rs
index 1e26d59f..e8d7f170 100644
--- a/src/js.rs
+++ b/src/js.rs
@@ -1078,6 +1078,14 @@ extern "C" {
     #[wasm_bindgen(method, js_class = "String", js_name = toString)]
     pub fn to_string(this: &JsString) -> JsString;
 
+    /// The toUpperCase() method returns the calling string value
+    /// converted to uppercase (the value will be converted to a
+    /// string if it isn't one).
+    ///
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase
+    #[wasm_bindgen(method, js_class = "String", js_name = toUpperCase)]
+    pub fn to_upper_case(this: &JsString) -> JsString;
+
     /// The trim() method removes whitespace from both ends of a string.
     /// Whitespace in this context is all the whitespace characters
     /// (space, tab, no-break space, etc.) and all the line terminator characters (LF, CR, etc.).
diff --git a/tests/all/js_globals/JsString.rs b/tests/all/js_globals/JsString.rs
index b6656bc5..0c937444 100644
--- a/tests/all/js_globals/JsString.rs
+++ b/tests/all/js_globals/JsString.rs
@@ -455,6 +455,32 @@ fn to_string() {
         .test()
 }
 
+#[test]
+fn to_upper_case() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section)]
+
+            extern crate wasm_bindgen;
+            use wasm_bindgen::prelude::*;
+            use wasm_bindgen::js;
+
+            #[wasm_bindgen]
+            pub fn string_to_upper_case(this: &js::JsString) -> js::JsString {
+                this.to_upper_case()
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                assert.equal(wasm.string_to_upper_case("Mozilla"), "MOZILLA");
+            }
+        "#)
+        .test()
+}
+
 #[test]
 fn trim() {
     project()