We report a boy affected by Shwachman syndrome (SS) who presented severe neutropenia and frequent suppurative infections, which we treated successfully with granulocyte colony-stimulating factor (rHuG-CSF). Daily injections of 7.5 micrograms/kg/day significantly increased the absolute neutrophil count and he was free from infections. In order to avoid the risk of side effects and to improve the child's quality of life, we intermittently administered lower doses of rHuG-CSF. A weekly dose of 2 micrograms/kg/day was able to maintain the absolute neutrophil count high enough (0.58-1.2 x 10(9)/L) to prevent suppurative infections. During the follow-up period (2.5 years) we tried suspending rHuG-CSF twice, but the absolute neutrophil count (0.18-0.31 x 10(9)/L) fell significantly and suppurative infections reoccurred (otitis, perianal abscess). rHuG-CSF may be a useful therapeutic agent in patients with symptomatic neutropenia in SS.