Thirty-eight patients undergoing elective hip or knee surgery were randomly allocated to two groups. Neuromuscular blockade in group A was antagonized with neostigmine 2.5 mg and atropine 1.2 mg, while group B received no drugs to facilitate antagonism of blockade. The incidence and severity of postoperative nausea and vomiting were assessed 24 h after operation. Nausea and vomiting were significantly reduced in group B. The incidence of nausea in group A was 68%, compared with 32% in group B (P less than 0.01). The incidence of vomiting was 47% in group A, compared with 11% in group B (P less than 0.02). A significant relationship was shown between postoperative emetic symptoms and the antagonism of neuromuscular blockade by neostigmine and atropine.