Background: Inadvertent enterotomy is a feared complication of adhesiotomy during abdominal reoperation. The nature and extent of this adhesion-associated problem are unknown. Methods: The records of all patients who underwent reoperation between July 1995 and September 1997 were reviewed retrospectively for inadvertent enterotomy, risk factors were analysed using univariate and multivariate parameters, and postoperative morbidity and mortality rates were assessed. Results: Inadvertent enterotomy occurred in 52 (19 per cent) of 270 reoperations. Dividing adhesions in the lower abdomen and pelvis, in particular, caused bowel injury. In univariate analysis body mass index was significantly higher in patients with inadvertent enterotomy (mean(s.d.) 25.5 (4.6) kg/m2) than in those without enterotomy (21.9(4.3) kg/m2) (P < 0.03). Patient age and three or more previous laparotomies appeared to be independent parameters predicting inadvertent enterotomy (odds ratio (95 per cent confidence interval) 1.9 (1.3-2.7) and 10.4 (5.0-21.6) respectively; P < 0.001). Patients with inadvertent enterotomy had significantly more postoperative complications (P < 0.01) and urgent relaparotomies (P < 0.001), a higher rate of admission to the intensive care unit (P < 0.001) and parenteral nutrition usage (P < 0.001), and a longer postoperative hospital stay (P < 0.001). Conclusion: The incidence of inadvertent enterotomy during reoperation is high. This adhesion-related complication has an impact on postoperative morbidity.