Rectus sheath hematoma (RSH) is a rare condition that's caused by a sudden disruption of the deep epigastric vessels or direct damage to the rectus abdominis muscle. This condition is associated with old age, childbirth, abdominal surgery, severe cough, severe sneezing, anticoagulation therapy and/or coagulation disorders. RSH is characterized by abdominal pain and an abdominal mass, so that this is often misdiagnosed as a surgical condition such as appendicitis, intraabdominal abscess, torsion of the ovary and ruptured abdominal aortic aneurysm; this can lead to unnecessary surgery. Thus, we have to be cautious not to miss RSH when a patient with predisposing factors is suffered from abdominal pain and an abdominal mass. We report here on a case of rectus sheath hematoma that was induced by severe cough in a patient who was taking warfarin.