Autoimmune haemolytic anaemia (AIHA) is a frequent complication of chronic lymphocytic leukaemia (CLL). The course of AIHA in CLL is quite variable and unpredictable. We report 9 patients who showed three distinct clinical patterns. Three patients had a single episode of AIHA which responded rapidly to oral prednisolone. Three others had a relapsing course often associated with a rising lymphocyte count which responded to a combination of prednisolone and cytotoxic drugs. The remaining three patients showed very little response to either form of treatment and continued to have haemolytic anaemia for the remainder of their lives. Development of AIHA did not appear to be associated with any particular stage of the disease and only patients with the third type of AIHA seemed to have a short survival.