PURPOSE: The aim of this study was to investigate the incidence and course of neutropenia following intravenous immunoglobulin (IVIG) therapy in children with idiopathic thrombocytopenic purpura (ITP). METHODS: From January 2001 to June 2006, fifty-four patients with ITP were enrolled in this study. Forty-two of 54 patients were treated with IVIG, while the other 12 were treated with anti-D immunoglobulin (Anti-D Ig). Post-treatment absolute neutrophil counts (ANC) were compared between patients who received IVIG and those who received Anti-D Ig. Comparison of post-treatment ANC between patients who treated with two different IVIG regimens (400 mg/kg/day for 5 days and 1 g/kg/day for 2 days) was also performed. RESULTS: Pretreatment ANC were not significantly different between the two treatment groups. After treatment with IVIG, 32 out of 42 patients (76.2%) showed more than 50% decrease of ANC from the baseline. On the other hand, only 2 out of 12 patients (16.7%) showed more than 50% decrease of ANC from the baseline after treatment Anti-D Ig. No significant difference was observed in the decline of ANC between the first IVIG treatment (42 patients) and repeated IVIG treatment groups (7 patients). There was no statistical difference in post-treatment ANC between patients who treated with two different IVIG regimens. The neutropenia induced by IVIG had resolved spontaneously in 38 out of 39 patients (97%) after several days. CONCLUSION: Neutropenia following IVIG administration may not be an uncommon finding in children with ITP. It seems to be transient and self limited.