Hemophagocytic syndrome is a rare but often fatal condition, and little is known about why this disorder can occur following surgery. We report herein the case of a patient successfully treated for a hemophagocytic syndrome-like condition that developed after emergency right hemicolectomy for a retroperitoneal abscess secondary to perforated colon cancer. The 62-year-old man initially presented after the sudden development of severe right back pain, and computerized tomography scans revealed a retroperitoneal abscess continuous with a tumor in the ascending colon. An emergency right hemicolectomy was subsequently performed. On postoperative day (POD) 2, his blood platelet count suddenly dropped to 1 x 10(4)/microl and histological examination of a bone marrow specimen taken on POD 5 showed abnormal histiocytes that had phagocytosed not only megakaryocytes, but also erythrocytes and leukocytes, and a normocellular marrow with a normal number of megakaryocytes. Hemophagocytic syndrome was suspected, and predonine was administered. The patient's condition improved remarkably and he was discharged on POD 51.