Ondansetron is a serotonin receptor antagonist which has been used frequently to reduce the incidence of post-operative nausea and vomiting in laparoscopic surgery. It has become very popular drug for the prevention of post-operative nausea and vomiting due to its superiority in-terms of efficacy as well as lack of side effects and drug interactions. Although cardiovascular adverse effects of this drug are rare, we found a case of symptomatic sinus bradycardia in a 43-year-old female patient, going for laparoscopic cholecystectomy, who developed the same after she was given intravenous ondansetron in operation theater during premedication. Hence, we report this case, as the rare possibility of encountering bradycardia effect after intravenous administration of ondansetron should be born in mind.