Four patients with proved Cushing's disease underwent spontaneous clinical and biochemical remission. They were part of an 11-patient group treated with methods that allowed spontaneous remission to be observed. Each patient was treated differently, one each with metyrapone tartrate, ketoconazole, bilateral adrenalectomy and adrenal autotransplantation, and no treatment. Spontaneous remission occurred 9 months to 5 years after diagnosis as evidenced by restoration of normal adrenal function occurring symptomatically in two patients and advent to hypoadrenalism with addisonian crisis in the two others. We conclude that spontaneous remission in Cushing's disease may not be a rare entity, although its actual incidence has yet to be established.