Severe cough may contribute to serious complications such as pneumothorax, pneumomediastinum, rib fracture, subconjunctival hemorrhage, subdural hemorrhage and cough syncope. However abdominal wall hematoma is a rare complication. Because it usually presents with abdomianal pain, abdominal wall hematoma needs to be differentiated from the acute surgical abdomen. A 78-year old woman was admitted with right lower quadrant abdominal pain and a palpable mass for several days. She experienced abdominal pain after violent coughing associated with an upper respiratory tract infection. Abdominal computed tomography revealed an approximately $7{ imes}4cm$ sized, ill-defined, soft tissue density lesion in the right lower posterolateral abdominal wall. An abdominal wall hematoma was diagnosed. After admission, she had persistent right lower abdominal pain and an increasing mass. The mass was surgically removed and she was discharged without complications. In summary, when a patient complains of abdominal pain after severe coughing, an abdominal wall hematoma as a differential diagnosis must be considered.