Clostridium difficile-related diarrhea and colitis are common health problems, especially in elderly, frail hospitalized patients. The drug of choice is metronidazole, which can be associated, in long or high doses, with neurotoxic side effects. We report convulsions induced by short-term metronidazole therapy used in conventional doses for Clostridium difficile colitis in an elderly patient with chronic renal failure.