Five patients, four of them with severe or severe generalized myasthenia gravis, were treated by long term orally administrated prednisolone, with following results: one complete remission and two almost complete remissions (in three aged fernale patients), two substantial improvements (one in a male patient, one in a young adult female patient, both thymectomized). The least favourable result was observed in the male patient. Positive results of such treatment were similarly reported by several authors (with an average of 70% complete or almost complete remission, 20% substantial improvement, 7% moderate improvement). These results appear qualitatively superior to those obtained with ACTH, and may be long-lasting. Treatment with prednisolone may be applied to any form of myasthenia gravis, particularly those which do not react to anticholinesterasic agents in moderate dosages. At onset of treatment, patients should be under care of a reanimation unit. Dosage is initially high (60--100 mg daily, secondarily on alternate days), and should be reduced very slowly, once a definite improvement is achieved. The duration of this treatment depends upon the results obtained: it should not last under one year. Associated treatment with anticholinesterasic agents remains disputable, whereas associated thymectomy seems to provide best results.