We present a sketch-based rotation editing system for enriching rotational motion in keyframe animations. Given a set of keyframe orientations of a rigid object

the user first edits its angular velocity trajectory by sketching curves

and then the system computes the altered rotational motion by solving a variational curve fitting problem. The solved rotational motion not only satisfies the orientation constraints at the keyframes

but also fits well the user-specified angular velocity trajectory. Our system is simple and easy to use. We demonstrate its usefulness by adding interesting and realistic rotational details to several keyframe animations.