We describe a case of an inflammatory pseudotumor of the spleen in a 5-year-old boy, found incidentally during a physical examination. The boy underwent a hemisplenectomy. The problems in differentiating this disease from lymphoma of the spleen before surgery and the advantages of hemisplenectomy are discussed. This rare disease has previously been described in the spleen in only 28 cases, the youngest being a 16-year-old patient.