We evaluated cyclosporine A (CsA) treatment in 9 patients (6 female and 3 male), 16-63 years old, with severe myasthenia gravis (MG) for a mean period of 2 years (range 16-36 months). All of the patients had been previously treated either with corticosteroids or by combined immunotherapy, and 5 needed periodic plasma exchanges. The reduction of plasmapheresis cycles in the 5 patients who needed periodic plasma exchange to maintain an acceptable quality of life showed an impressive cost-benefit analysis. During CsA treatment 7 of 9 patients improved their muscle strength and functional score. In all the patients except one the corticosteroid dosage was reduced and in 7 of the 9 patients the dose reduction was over 50% with subsequent reduction of the corticosteroid side effects. The findings showed that initiation of CsA treatment increased muscle strength and reduced corticosteroid dosage. The most common CsA side effects were: a serum creatinine increase that occurred in the first 6-12 months of therapy in 8 patients, other side effects like hypertrichosis and gingival hyperplasia were present in four patients. Blood pressure increase was found in only one patient. CsA treatment may be a valuable and cost effective treatment in severe MG.