To determine whether intravenous ketoprofen is effective as pre-emptive analgesia for breast surgery.Randomised, controlled, double blind study.50 patients undergoing breast surgery under general anaesthesia randomised to receive either 100 mg intravenous ketoprofen 30 minutes before (Group I), or immediately after surgical incision (Group II). Postoperatively, pain scores (Visual Analogue Scale, VAS) and time to rescue analgesic were recorded by an independent, blinded observer. The study was terminated when rescue analgesic was required (VASor =4 or demand for analgesic).Continuous variables were analysed by the unpaired 't' test, discrete variables with the chi square test, and survival curves by the log-rank test.Pain scores were significantly lower in Group I till 10 hours after surgery. The number of patients requiring analgesia at 4, 6, 8 and 10 hours was significantly lower in group I (0% vs. 47% [P0.0001], 0% vs. 44% [P0.003], 0% vs. 80% [P0.0001], 0% vs. 100% [P0.0001] respectively). The mean time for rescue analgesic was 15.47 -/+ 2.87 hours in group I versus 4.22 -/+ 2.55 hours in group II (P0.0001).Pre-emptive analgesia with Intravenous ketoprofen (100mg) produces better postoperative pain-relief in patients undergoing breast surgery.