To assess in a retrospective analysis if there is evidence suggesting corticosteroids can prevent the neurologic complications of intravenous immunoglobulin (IVIG) therapy in children with immune thrombocytopenic purpura (ITP). From March 1985 to September 1997, 112 children received IVIG (1 g/kg/day for one or two dosages) for the treatment of ITP. During the years 1990 to 1997, 23 children nonrandomly received a short course of prednisone (2 mg/kg/day during and for 3 days after the completion of IVIG therapy) as a prophylaxis against the neurologic complications of IVIG therapy. The authors analyzed the data of all 112 children and compared the incidence of neurologic complications in those who received prednisone prophylaxis with those who did not. The severity of the complications was assessed as follows: grade 1, headache only; grade 2, headache plus vomiting; grade 3, headache, vomiting, and fever; grade 4, headache, vomiting, fever, and meningeal signs (aseptic meningitis). Of the 23 children who received prednisone prophylaxis, 2 (8.7%) experienced headache and vomiting after the completion of prednisone prophylaxis. Of the 89 children without prednisone prophylaxis, 27 (30.3%) experienced neurologic symptoms of varying severity, including one patient with aseptic meningitis proven by examination of the spinal fluid. Twelve of these patients needed additional hospital care for the complications. Children receiving prednisone had a 78% lower risk of neurologic complications (OR = 0.22; CI = 0.05-0.90; P = 0.036). This retrospective study shows a short course of prednisone therapy, given during and until 3 days after the completion of IVIG infusion, is likely to decrease the incidence and severity of neurologic complications of IVIG in children with ITP.