Nitroimidazoles have been used alone or in combination with other antibacterial agents in the treatment of brain abscess. They are associated with certain adverse reactions related primarily to the gastrointestinal tract and central nervous system. But, as far as we know, cardiac arrest due to ornidazole has not been reported in the literature. In this study, we presented a case in which cardiac arrest occurred as an unusual side-effect of intravenous ornidazole administered to a ten-year-old girl suffering from brain abscess.