This case describes a 34-year-old female who developed severe chorea following intravenous administration of ondansetron after elective caesarean section under spinal anaesthesia. A course of benztropine led to a decrease in severity of the reaction which resolved on the fifth postoperative day. Ondansetron is believed to cause extrapyramidal reactions through actions on 5HT 3 receptors in the basal ganglia. Whereas isolated case reports of extrapyramidal reactions to ondansetron do exist, they have typically been associated with higher doses and have resolved within hours. We report the lengthiest extrapyramidal reaction to ondansetron yet described.