Forty-four children with autoimmune haemolytic anaemia (AIHA) are described: 31 had acute, subacute or chronic disease with warm autoantibodies and 13 had acute or chronic anaemia with cold autoantibodies. The commonest forms were the acute and subacute types with warm autoantibodies and these were more frequent in young children, while chronic AIHA occurred mainly among children at puberty. In about 16% the anaemia was accompanied by a chronic disorder but in over 50% the anaemia was preceded by an acute infection or immunization. The former gave rise mainly to chronic anaemia, but the latter was associated with the acute and subacute forms. In general the prognosis was good and death was never caused by anaemia per se. The prognosis was worse in patientw with clinical features of thrombocytopenia and bleeding and with the immunological findings of free autoantibodies in the serum and a positive direct antiglobulin test. In acute and subacute forms, treatment with corticosteroids and sometimes with blood transfusions was effective. In chronic forms of the disease it was often necessary to give additional immunosuppressive drugs or/and to perform a splenectomy.