This study examined the effects of wrist rest and forearm support on reducing computer operators' activities using the trapezius, deltoid, biceps brachii, extensor carpi radialis longus, and extensor digitorum. 12 young (M= 25.9 yr., SD= 2.4) men were asked to perform both static and dynamic mouse operations in four conditions, two using a wrist rest and two using a forearm support. Analysis showed that use of the forearm support had a significant effect on reducing the EMG activity in muscles of the trapezius, deltoid, biceps brachii, extensor carpi radialis longus, and extensor digitorum. However, the wrist rest only significantly reduced deltoid and extensor carpi radialis longus activities.