POSSUM and APACHE II scores from 117 consecutive admissions to a high-dependency unit after major surgery were correlated with 30-day morbidity and mortality rates. Thirteen patients (II per cent) died and 59 (50 per cent) developed a postoperative complication. Receiveroperating characteristic curve analysis showed POSSUM to have good predictive value for mortality (area under curve 0.75) and morbidity (area under curve 0.82). APACHE II scores had a significantly inferior predictive value for mortality (area under curve 0.54) (P < 0.002). POSSUM was superior to APACHE II in prediction of mortality in patients admitted to a high-dependency unit after general surgery. Prediction of postoperative complications by POSSUM is accurate and may be useful for audit.