This prospective, randomized and double-blinded study was designed to evaluate the anti-emetic efficacy of a combination of ondansetron and metoclopramide in 100 ASA physical status I and II children of either sex and 1–15 years of age undergoing elective surgery for strabismus. A standardized anaesthetic technique and post-operative analgesia were used for all the children. Children were divided into four groups. They received saline, metoclopromide 250 μg kg−1, ondansetron 150 μg kg−1 or a combination of metoclopramide 150 μg kg−1 and ondansetron 100 μg kg−1 intravenously immediately after the insertion of an intravenous cannulae. There were no differences between the groups in their age, gender, weight, duration of surgery, number of muscles subjected to surgery or intravenous fluids received. In the first 24 post-operative hours, 18 (72%) patients in the placebo group, 15 (60%) patients in the metoclopramide group, 10 (40%) patients in the ondansetron group and 11 (44%) patients in the combination group had nausea or vomiting. The overall incidence of post-operative nausea and vomiting was significantly (P<0.05) lower in the combination group and in the ondansetron group compared with the placebo group. Nine (36%) patients in both the placebo and the metoclopramide groups and one (4%) patient in the ondansetron group required rescue anti-emetic treatment. None of the patients in the combination group required rescue anti-emetic and this was significantly less (P <0.01) when compared with the placebo and the metoclopramide groups. Recovery and sedation scores were comparable in all the four groups. A combination of metoclopramide 150 μg kg−1 and ondansetron 100 μg kg−1 administered prior to surgery was not found to be more effective than ondansetron 150 μg kg−1 alone for the prophylaxis of nausea and vomiting following surgical repair of strabismus in paediatric patients.