We have studied the addition of droperidol to morphine during patient-controlled analgesia (PCA) in 57 patients using PCA after abdominal hysterectomy. Patients in group 1 (control group) received placebo at induction of anaesthesia and a PCA containing morphine; those in group 2 received droperidol 1.25 mg and a PCA containing morphine and those in group 3 droperidol and a PCA containing droperidol 0.05 mg mg-1 of morphine. Patients in the control group suffered 51 episodes of nausea compared with 35 in the droperidol bolus group and 18 in the droperidol PCA group (P < 0.01). In the droperidol PCA group, only 10 doses of additional antiemetic therapy were required compared with 24 in the droperidol bolus group and 28 in the control group (P < 0.05). We did not observe side effects attributable to droperidol. We conclude that droperidol added to morphine in PCA reduces nausea and antiemetic requirements after abdominal hysterectomy.