A 6-week-old infant had autoimmune hemolytic anemia. Serological studies disclosed a strong, warm, panagglutinating autoantibody showing no Rh specificity. There was also a significant rise in titer to cytomegalovirus. Treatment consisted of transfusions of sedimented red blood cells, two exchange transfusions, and administration of corticosteroids. The infant has been symptom-free for five months and has had a negative Coombs test and a normal hemogram.