This study aimed to evaluate the efficacy, cost, and effects of anti-D immunoglobulin (anti-D Ig), methylprednisolone, or intravenous immunoglobulin (IVIG) therapy on the development of chronic disease in children who are Rh-positive with diagnosed immune thrombocytopenic purpura (ITP). Children with newly diagnosed ITP and platelet count <20,000/mm(3) were prospectively randomized to treatment with anti-D Ig (50 μg/kg), methylprednisolone (2 mg/kg/day), or IVIG (0.4 g/kg/day, 5 days). Sixty children with a mean age of 6.7 years were divided into three equal groups. No difference was observed between platelet counts before treatment and on day 3 of treatment. However, platelet counts at day 7 were lower in the methylprednisolone group than in the IVIG group (P = 0.03). In the anti-D Ig group, hemoglobin and hematocrit levels were significantly lower at the end of treatment (P < 0.05). Chronic ITP developed in 30% of the anti-D Ig group, 35% of the methylprednisolone group, and 25% of the IVIG group, but no significant difference was noted among the groups. The cost analysis revealed that the mean cost of IVIG was 7.4 times higher than anti-D Ig and 10.9 times higher than methylprednisolone. In the treatment of ITP in childhood, one 50 μg/kg dose of anti-D Ig has similar effects to IVIG and methylprednisolone. Among patients who were treated with anti-D Ig, serious anemia was not observed, and the cost of treatment was less than that of IVIG treatment.