Neuropsychological evaluations were performed on 15 myasthenics and 11 control patients with polymyositis/dermatomyositis (PM/DM). The test battery included subtests of Wechsler Memory Scale-Revised, Boston Naming Test, Word Fluency, Trail Making A Test, and Rey Complex Figure. There were no significant differences between the MG and the PM/DM patients on these measures. These results do not support those reported by other researchers whose results suggested cognitive impairment in memory and language functioning. © 1994 Raven Press, Ltd., New York.