Tetanus is a neurologic disorder caused by a tetanospasmin released from Clostridium tetani and usually occurs following a stab wound or dirty abrasion. Tetanus is uncommon in Korea due to the introduction of vaccination programs. Furthermore, tetanus associated with a gangrenous perforation of the small bowel is extremely rare. We report a case of tetanus developed in a patient who was diagnosed with a gangrenous perforation of the small bowel. This is the first reported case in Korea.