VINCRISTINE sulfate and vinblastine sulfate are dimeric alkaloids isolated from the periwinkle plant, Vinca rosea. Both of these agents have proven useful in inducing remission in leukemia, either alone or in concert with other agents. Their use, however, is often accompanied by evidence of nerve and muscle damage. The most common findings are dysesthesias,1anesthesia, and parasthesias in the fingers and toes,2loss of deep tendon reflexes in the lower extremities, weakness of extensors, foot drop, and ataxia.3,4In some cases this neuropathy has been reported to be reversible,2while in others no reversibility has been evident.3Moress and his co-workers1have recently reported three cases in which severe and irreversible neuropathy was associated with vincristine therapy. A varying degree of axonal degeneration and myelin loss was seen in the peripheral nerves of these patients. The development of spheromembranous bodies in the muscles