diff --git a/dlls/vbscript/global.c b/dlls/vbscript/global.c
index eaf4383e56b..a812d91f332 100644
--- a/dlls/vbscript/global.c
+++ b/dlls/vbscript/global.c
@@ -122,6 +122,30 @@ static HRESULT to_int(VARIANT *v, int *ret)
     return S_OK;
 }
 
+static HRESULT to_string(VARIANT *v, BSTR *ret)
+{
+    static const WCHAR trueW[] = {'T','r','u','e',0};
+    static const WCHAR falseW[] = {'F','a','l','s','e',0};
+
+    switch(V_VT(v)) {
+    case VT_BOOL:
+        *ret = SysAllocString(V_BOOL(v) ? trueW : falseW);
+        return *ret ? S_OK : E_OUTOFMEMORY;
+    default: {
+        VARIANT dst;
+        HRESULT hres;
+
+        V_VT(&dst) = VT_EMPTY;
+        hres = VariantChangeTypeEx(&dst, v, MAKELCID(MAKELANGID(LANG_ENGLISH,SUBLANG_ENGLISH_US),SORT_DEFAULT), 0, VT_BSTR);
+        if(FAILED(hres))
+            return hres;
+
+        *ret = V_BSTR(&dst);
+        return S_OK;
+    }
+    }
+}
+
 static IUnknown *create_object(script_ctx_t *ctx, const WCHAR *progid)
 {
     IInternetHostSecurityManager *secmgr = NULL;
@@ -564,8 +588,33 @@ static HRESULT Global_LCase(vbdisp_t *This, VARIANT *arg, unsigned args_cnt, VAR
 
 static HRESULT Global_UCase(vbdisp_t *This, VARIANT *arg, unsigned args_cnt, VARIANT *res)
 {
-    FIXME("\n");
-    return E_NOTIMPL;
+    BSTR str;
+    HRESULT hres;
+
+    TRACE("%s\n", debugstr_variant(arg));
+
+    if(V_VT(arg) == VT_NULL) {
+        if(res)
+            V_VT(res) = VT_NULL;
+        return S_OK;
+    }
+
+    hres = to_string(arg, &str);
+    if(FAILED(hres))
+        return hres;
+
+    if(res) {
+        WCHAR *ptr;
+
+        for(ptr = str; *ptr; ptr++)
+            *ptr = toupperW(*ptr);
+
+        V_VT(res) = VT_BSTR;
+        V_BSTR(res) = str;
+    }else {
+        SysFreeString(str);
+    }
+    return S_OK;
 }
 
 static HRESULT Global_LTrim(vbdisp_t *This, VARIANT *arg, unsigned args_cnt, VARIANT *res)
diff --git a/dlls/vbscript/tests/api.vbs b/dlls/vbscript/tests/api.vbs
index 67c365d1a04..fe6f9b0b940 100644
--- a/dlls/vbscript/tests/api.vbs
+++ b/dlls/vbscript/tests/api.vbs
@@ -145,4 +145,18 @@ TestMid2 "test", 2, "est"
 TestMid2 "test", 4, "t"
 TestMid2 "test", 5, ""
 
+Sub TestUCase(str, ex)
+    x = UCase(str)
+    Call ok(x = ex, "UCase(" & str & ") = " & x & " expected " & ex)
+End Sub
+
+TestUCase "test", "TEST"
+TestUCase "123aBC?", "123ABC?"
+TestUCase "", ""
+TestUCase 1, "1"
+TestUCase true, "TRUE"
+TestUCase 0.123, "0.123"
+TestUCase Empty, ""
+Call ok(getVT(UCase(Null)) = "VT_NULL", "getVT(UCase(Null)) = " & getVT(UCase(Null)))
+
 Call reportSuccess()