BACKGROUND Rectus sheath hematoma (RSH) is one of the rare causes of acute abdominal pain. This clinical entity is frequently misdiagnosed and leads to unnecessary surgical intervention. We investigated the critical points of the diagnosis and therapy in preventing these mistakes. METHODS Five patients (5 females; mean age 67.4; range 53 to 74 years) admitted to the emergency surgery unit and diagnosed as RSH between December 2000 and July 2005 were reviewed retrospectively. Demographic characteristics, medical history complaints and physical examination, laboratory and imaging studies findings were investigated. RESULTS Four patients had been receiving anticoagulant therapy. All of the cases were complaining of abdominal mass and abdominal pain. In the physical examination painful mass was palpated. In cases anemia determined, the diagnosis was done only by computed tomography (CT) in one case, by ultrasonography (USG) and CT in three cases, and during surgical exploration for acute abdomen in one case. Blood transfusion was administered in all of the cases. In four patients anticoagulant therapies were discontinued and intravenous vitamin K and fresh frozen plasma were administered. In one case bleeding control was done during the operation. While three cases were discharged uneventfully following mean hospital stay of 13.6 days, two cases died on the fifth and seventh days. CONCLUSION In elderly patients with acute abdominal pain, infraumblical mass, anemia and history of anticoagulation therapy, RSH should be taken into consideration and USG and CT should be performed. Early and accurate diagnosis helps for a successful medical treatment and prevents unnecessary surgical intervention.