['Postoperative nausea and vomiting after anesthesia is an distressing side effect. This study was undertaken to determine to what extent spinal opioids contribute to postoperative nausea and vomiting (PONV) and secondly to how effectively metoclopramide can reduce the incidence of PONV after intrathecal administration of morphine.', 'Patients were allocated to three groups all undergoing major joint surgery of the lower limb. In group 1 (n = 200), intrathecal anesthesia was assessed by administration of 20 mg bupivacaine and 0.2 mg morphine. In Group 2 (n = 100) intrathecal anesthesia was assessed in the same way and in addition, 20 mg metoclopramide intramuscular during maintenance of anesthesia and a second dose of 20 mg metoclopramide was administered intramuscular after arrival at the recovery room. Finally, in group 3 (n = 100), intrathecal anesthesia was assessed after administration of 20 mg bupivacaine.', 'The maximum PONV percentages were 41.1%, 32.7%, and 37% in groups 1, 2, and 3, respectively. The consumption of antiemetics was similar in all groups. The number of patients who needed one or more additional antiemetics during the first 24 hours after surgery was 112 (56.6%), 57 (58%), and 60 (60%) in groups 1, 2, and 3, respectively.'] Is intrathecal addition of morphine to bupivacaine the cause of postoperative nausea and vomiting?