The effects of targeted strength training in patients with muscle weakness of central origin following cerebrovascular accidents has hardly been investigated to date. This prospective non-randomized study of 56 patients was designed to shed light on the effects of strength building exercises on muscle tone and on the gain in muscle strength achieved with them. All patients underwent a full residential neurologic rehabilitation program for 4 weeks, which included an exercise program for restoring the extensor strength of the legs and the supporting strength of the arms by leg and arm presses. Throughout the rehabilitation program muscle spasticity was evaluated clinically and maximal muscle strength on completion of the exercise program was compared to baseline. The extensor strength of the legs increased by 31.0 (+/- 26.7)% by 40.2 (+/- 15)%. significant for both variables. The extent of strength gain was positively correlated with the intensity and the number of exercising units. Muscle tone, which was abnormally high at baseline, did not further increase in any one case. The results of this study showed that targeted strength training significantly increased muscle power in patients with muscle weakness of central origin without any negative effects on spasticity.