diff --git a/dlls/jscript/math.c b/dlls/jscript/math.c
index 2928a97c56..1969ff7bb0 100644
--- a/dlls/jscript/math.c
+++ b/dlls/jscript/math.c
@@ -543,8 +543,22 @@ static HRESULT Math_sqrt(DispatchEx *dispex, LCID lcid, WORD flags, DISPPARAMS *
 static HRESULT Math_tan(DispatchEx *dispex, LCID lcid, WORD flags, DISPPARAMS *dp,
         VARIANT *retv, jsexcept_t *ei, IServiceProvider *sp)
 {
-    FIXME("\n");
-    return E_NOTIMPL;
+    VARIANT v;
+    HRESULT hres;
+
+    TRACE("\n");
+
+    if(!arg_cnt(dp)) {
+        if(retv) num_set_nan(retv);
+        return S_OK;
+    }
+
+    hres = to_number(dispex->ctx, get_arg(dp, 0), ei, &v);
+    if(FAILED(hres))
+        return hres;
+
+    if(retv) num_set_val(retv, tan(num_val(&v)));
+    return S_OK;
 }
 
 static const builtin_prop_t Math_props[] = {
diff --git a/dlls/jscript/tests/api.js b/dlls/jscript/tests/api.js
index 54fc2a1582..c1da8c8c05 100644
--- a/dlls/jscript/tests/api.js
+++ b/dlls/jscript/tests/api.js
@@ -878,6 +878,33 @@ ok(tmp === Infinity, "Math.sqrt(Infinity) = " + tmp);
 tmp = Math.sqrt(-Infinity);
 ok(isNaN(tmp), "Math.sqrt(-Infinity) is not NaN");
 
+tmp = Math.tan(0);
+ok(tmp === 0, "Math.tan(0) = " + tmp);
+
+tmp = Math.tan(Math.PI);
+ok(Math.floor(tmp*100) === -1, "Math.tan(Math.PI) = " + tmp);
+
+tmp = Math.tan(2, 2);
+ok(Math.floor(tmp*100) === -219, "Math.tan(2, 2) = " + tmp);
+
+tmp = Math.tan(true);
+ok(Math.floor(tmp*100) === 155, "Math.tan(true) = " + tmp);
+
+tmp = Math.tan(false);
+ok(tmp === 0, "Math.tan(false) = " + tmp);
+
+tmp = Math.tan();
+ok(isNaN(tmp), "Math.tan() is not NaN");
+
+tmp = Math.tan(NaN);
+ok(isNaN(tmp), "Math.tan(NaN) is not NaN");
+
+tmp = Math.tan(Infinity);
+ok(isNaN(tmp), "Math.tan(Infinity) is not NaN");
+
+tmp = Math.tan(-Infinity);
+ok(isNaN(tmp), "Math.tan(-Infinity) is not NaN");
+
 var func = function  (a) {
         var a = 1;
         if(a) return;