A 28 year old female patient with Cushing's syndrome due to an adrenal adenoma also suffered from recurrent urinary infections (proteus), tonsillitis (streptococcus), permanent candidiasis and perimandibular abscess (Staphylococcus pyogenes). Suppression of cellular and humoral immunity was confirmed by in vitro tests. After successful right adrenalectomy the clinical signs of Cushing's syndrome disappeared and no evidence of either bacterial or fungal infection were noted one year postoperatively. Immunological tests showed the restitution of both cellular and humoral immunity. The course of the disease in the patient supports the idea that Cushing's syndrome might be considered as a transitory immune deficiency state.