Acute visual loss, pain, and redness in the left eye developed in a 61-year-old diabetic man. Results of ophthalmologic examination showed 4+ conjunctival hyperemia and chemosis, no light perception, and restricted ocular motility. Through a hazy cornea, a gas bubble was visualized filling about 50% of the anterior chamber. A vitreous tap disclosed myriad gram-positive rods with terminal and subterminal spores. Cultures of the vitreous grew Clostridium septicum, a gas-forming organism. Exploratory abdominal laparotomy showed a ruptured diverticulum of the sigmoid colon with acute peritonitis. In spite of intensive antibiotic therapy, the patient died approximately 24 hours after admission. Results of histopathologic examination of the postmortem left eye demonstrated massive necrosis of the intraocular structures with numerous gram-positive rods confined mainly to the retinal pigment epithelium (RPE), detached retina, and vitreous. To the best of the authors' knowledge, this is the second reported case of C. septicum panophthalmitis. Only 69 cases of clostridial infections with ocular involvement have been recorded previously in the literature.