350 patients with idiopathic thrombocytopenic purpura (ITP) aged 2/12-15 years (mean 6.3 +/- 2.7) were followed up during the period January 1st, 1975 to March 31, 1992. They constituted 40% of cases with hemorrhagic diathesis attending the Hematology/Oncology Clinic, Children's Hospital, Ain Shams University (relative frequency of 37.4/100.000 of the general Out-Patient Clinic in the same hospital). These patients presented with acute (71.4%), chronic (22.9%) and recurrent (5.7%) forms. The age of presentation was younger in acute ITP. In the recurrent form there was significant female predominance. Most cases of acute ITP (66%) presented in winter and spring, with a positive history of preceding viral illness in 50% in contrast to 10% in chronic form. Four chronic ITP cases developed lupus erythematosus; all were females > 9 years. As regards therapy, acute ITP cases with initial platelet count (PC) < 10 x 10(9)/l were randomized to receive either high-dose methyl prednisolone (HDMP) 10 mg/kg/day for 5 days i.v. (n = 10) or intravenous immunoglobulin (IVIG) 0.4 g/kg/day for 5 days (n = 10) or conventional-dose prednisone (CDP) 2 mg/kg/day 4 weeks p.o. (n = 10). A dramatic response was noticed in the first two groups. In chronic ITP, (n = 80) CDP induced complete response (CR) in 30% and partial response (PR) in 20%; 50% were nonresponders. Twenty-four refractory ITP with persistent PC < or = 20 x 10(9)/l received second-line therapy: vincristine 1.5 mg/m2/week i.v. 4 doses (n = 4) with no clinical or hematological improvement. IVIG 0.4 g/kg/day for 5 days (n = 8) with sustained CR only in 2 patients (25%) and PR in 2 patients (25%). Splenectomy was performed (n = 12) with CR in 50%; out of them, 2 patients had shown no improvement on prior IVIG therapy. In conclusion, ITP is a benign condition with no fatality reported, but it could run a chronic refractory course.