The value of postoperative monitoring of intra-abdominal pressure (IAP) in surgical patients has not been established. This study prospectively evaluated the occurrence of increased IAP and its association with renal impairment and outcome in surgical patients admitted to an intensive care unit. One hundred consecutive patients after laparotomy were studied, 88 of whom had complete IAP measurements. IAP was measured using an intravesical catheter and was considered increased when equal to 20 mmHg or above. Renal impairment was defined as a postoperative serum creatinine concentration of greater than 130 mumol/l, or an increase in serum creatinine of greater than 100 mumol/l within 72 h of surgery. The median (range) APACHE (Acute Physiology And Chronic Health Evaluation) II score of the patients was 13.5 (4-43). The incidence of raised IAP was 29 of 88 (33 per cent). Renal impairment was present in 29 of 88 (33 per cent), of whom 20 of 29 (69 per cent) had raised IAP (P < 0.01). The odds ratios (95 per cent confidence interval) for the development of renal impairment and death in patients with increased IAP were 12.4 (3.8-41.7) and 11.2 (2.8-47.9) respectively. There is a clinically significant association between increased IAP and renal impairment in patients admitted to an intensive care unit after laparotomy.