Fourteen adults underwent cardiac surgery with a standard anaesthetic technique. Prior to surgery and the day after surgery, gastric emptying was determined using the paracetamol absorption technique. Results from 13 patients were available for analysis. The mean time to reach the maximum plasma concentration was 14.1 min (SEM 2.1) pre-operatively and 225.4 min (SEM 42.3) postoperatively. The mean maximum concentration was 23.7 mg.l-1 (SEM 1.9) pre-operatively and 5.1 mg.l-1 (SEM 0.8) postoperatively. The area under the curve (0-60 min) was 892 mg min.l-1 (SEM 57) pre-operatively and 131 mg min.l-1 (SEM 25) postoperatively. The differences between pre- and postoperative values were highly significant for all these three measurements. We conclude that gastric emptying is markedly delayed the day after elective cardiac surgery.