While iodoform gauze has a good antiseptic effect, cases of iodoform toxicity are not common. Iodoform can cause neurological symptoms such as disturbance of consciousness, and intoxication occurs with relative ease under certain suitable conditions. Medical practitioners may often misdiagnose disturbance of consciousness for various reasons, and the actual cause of disturbance of consciousness should be clarified. We now report a case of prolonged disturbance of consciousness caused by the use of iodoform gauze in the treatment of necrotizing fasciitis. A 70-year-old diabetic female, who used insulin injections, acquired necrotizing fasciitis in her left buttock and underwent surgery involving release of purulent discharge and debridement. The surgical area was packed with iodoform gauze following surgery, and the gauze was replaced daily. The patient's general condition gradually improved, but disturbance of consciousness, around Glasgow coma scale E2VTM4, was prolonged. We discontinued iodoform gauze treatment, following which consciousness improved slowly. The blood serum iodine level was too high. Although we often use iodoform gauze as an effective treatment for infected sites, we must take heed of its potential toxic neurological effects.