Between 1979 and 1990 we have seen 8 patients (7 females) with rheumatoid arthritis (RA) who developed a neuro-muscular involvement while on D-penicillamine (D.P.). Five of them had a drug-induced myasthenia. D.P. withdrawal led to a complete recovery in 1.5 to 5 months. Another patient presented with a myopathy which led to the diagnosis of Grave's disease. She was treated with D.P. for 4 months. D.P. was reintroduced and 5 months later a myasthenic syndrome developed. A thymoma was discovered 1 year later. In the last 2 patients D.P. induced polymyositis which, in one, was associated with features of systemic lupus erythematosus. In the other patient, the evolution was fatal in spite of D.P. withdrawal, high dose steroids and plasma exchanges. A literature survey has shown 150 D.P. induced myasthenia and 38 D.P. induced polymyositis cases.