The incidence of AITP is 20-30/million/year. The diagnosis is based on the finding of an isolated thrombocytopenia without other blood abnormalities and absence of a palpable spleen. Additional tests such as bone marrow examination, determination of platelet antibodies and of thrombopoetin are required only in special cases. The usual first line therapy in patients with bleeding tendency and a low platelet count is prednisolone at a dose of 1 mg/kg/day. Patients who have platelet counts of less than 20,000/microl 3-6 months after steroid therapy are candidates for splenectomy, in particular if more than 0.1 mg/kg/day prednisolone is required to keep the patient free of bleedings. Laparoscopic splenectomy has a low mortality (0.2%) and morbidity (10%). The risk of post-splenectomy overwhelming pneumococcal septicaemia can be minimized by preoperative vaccination. Older patients, who have low platelet counts after splenectomy, have a high bleeding risk. The most effective treatment options for these patients are cyclophosphamide, azathioprine and rituximab, but the choice of treatment should be carefully considered, since the risk of adverse effects may be greater than the risk of fatal bleeding.