Nontraumatic Clostridium septicum infections may present as either septicemia or as metastatic myonecrosis. Most of these infections occur in debilitated patients with diabetes who are receiving cancer chemotherapy. The majority have a hematologic abnormality or a carcinoma of the colon. Usually there is an ulcerative lesion of the gastrointestinal tract that serves as the portal of entry. While most of these patients die from overwhelming sepsis, our patient was debrided early and treated promptly with high-dose penicillin therapy as well as hyperbaric oxygen therapy. He fully recovered from C. septicum gas gangrene and underwent resection of a recurrent colonic cancer.