The autoimmune haemolytic anaemias are common syndromes, with protean clinical features reflecting a variety of significant associated diseases. A diagnosis of this state should alert the clinician to the possibility of an aberrant immune mechanism. Years may elapse between development of the haemolytic process and the eventurl emergence of the entire disease pattern. The haemolytic anaemia should be considered as the easily diagnosed part of a complex, multisystem disease resulting from malfunction of the immune apparatus. Therapy can be exceedingly difficult. The following outline is suggested as a general approach: 1. Start prednisone 60 mg daily. If a therapeutic response occurs, continue this dosage until the haematocrit reaches 30 per cent. A slow but progressive reduction should then be initiated. 2. If prednisone dosages greater than 15 mg daily are required to maintain the remission, treat as a therapeutic failure. 3. If no response occurs after one week of prednisone, start azathioprine 2.0 to 2.5 mg/kg. 4. If no response is apparent after two additional weeks (three weeks of prednisone), progressively reduce and eventually discontinue prednisone. 5. If no response occurs after a total of four weeks of azathioprine, one of two alternative therapies should be started: (a) perform splenectomy, or (b) increase azathioprine by 25 mg daily, every one to two weeks, until either a response occurs or reduced bone marrow function is observed. 6. If azathioprine and splenectomy both fail, experimental therapies such as antithymocyte antiserum or thymectomy should be considered. 7. Transfusions are to be used only as temporary paliation in life-threatening neurological or cardiovascular complications.