The contrasting results of treatment of patients with postoperative enterocutaneous fistulae reflect the heterogeneity of the disease and depend on the patient's condition and the characteristics of the fistulae. For this reason, the use of a prognostic index, which enables such patients to be classified according to their risk of death, could be useful. In this study we propose a prognostic index based on a logistic regression analysis, obtained by using two (APACHE II score and serum albumin concentration) of the eight risk factors that have been retrospectively analysed in a series of 70 patients with postoperative enterocutaneous fistulae treated in our surgical department since 1981. The logistic regression equation indicates that patients with a probability of dying of less than 0.35 have a good prognosis, with a sensitivity of 90 per cent, a specificity of 90 per cent, a negative predictive value of 79 per cent, a positive predictive value of 96 per cent and an accuracy of 90 per cent. The predictive performance of the index has also been evaluated in a group of 17 patients studied prospectively, and this confirms the sensitivity and specificity of the model. This postoperative enterocutaneous fistulae index could be a helpful tool in clinical trials and surgical audit.