The most common cause of mortality in childhood acute idiopathic thrombocytopenic purpura (ITP) is intracranial hemorrhage (ICH), which occurs in about 0.1% of children with platelet counts below 20,000/microl. Forty-two children (1-13 years) with ITP and platelet counts < or = 20,000/microl were randomly divided into two groups. Twenty patients received mega-dose methylprednisolone (MDMP) in a dosage of 30 mg/kg/d for three days and 20 mg/kg/d for four days. Twenty-two patients received intravenous immunoglobulin (IVIG) in a dosage of 1 g/kg/d two days. Platelet counts of the patients were determined at diagnosis, at 2, 4, 7, 14, 30, 60, 90, 120, 150, and 180 days and at three-month intervals after the 6th month. The mean platelet counts of both groups gradually increased and peaked on the 7th day (p > 0.05). There were no significant differences between the mean platelet counts of patients, in the two groups on treatment days 0, 2, 4, 7, and 14. The mean time for achievement of platelet counts above 20,000/microg in the MDMP group and the IVIG group was 4.1 and 2.9 days (p < 0.05) and above 50,000/microl was 5.0 and 5.2 days (p > 0.05), respectively. The percentages of patients with platelet counts above 20,000/microl at the 2nd day of the treatment were 50% in the MDMP group, and 86% in the IVIG group (p < 0.05). No significant differences were observed in the mean platelet counts of the two groups treatment days 30, 60, 90, 120 and 180 (p > 0.05). Chronic ITP developed in five patients (25%) in the MDMP group, and in four patients (18%) in the IVIG group (p > 0.05). Intravenous immunoglobulin (IVIG) (1 g/kg/d for 2 days) and MDMP treatments (30 mg/kg/d for 3 days, 20 mg/kg/d for 4 days, perorally) are equally effective in the treatment of acute ITP. Because of its nonbiologic source, lower cost, fewer side effects and oral use, we prefer oral preparations of MDMP in the treatment of childhood ITP.