We have studied the analgesic and morphine sparing effect of ketorolac tromethamine in 60 patients after total hip replacement under spinal anesthesia. In this double blind study 30 patients received ketorolac 30 mg IM 6 hourly postoperatively and the control group received saline. Analgesia was assessed by visual analogue pain scores (VAS) and morphine consumption by patient controlled analgesia (PCA). There was a significantly (P < 0.02) lower morphine consumption in the ketorolac group (7.1 +/- 8.6 mg; Mean +/- s.d.) when compared to the saline group (14.2 +/- 13.6 mg). Although there was a trend for lower VAS on the first postoperative night this was only significant at 10 hours postoperatively and the next morning at 08:00 hr. The incidence of side effects (emetic sequelae, pruritus and headache) were similar in both groups. It is concluded that ketorolac reduces the consumption of additional morphine in conjunction with intrathecal morphine but had no effects on the side effects.