BACKGROUND: Postoperative outcomes were studied in relation to adverse nutritional risk (body mass index (BMI) below 20 kg/m(2)), advanced age (80 years or more) and co-morbidity (American Society of Anesthesiologists (ASA) grade III-IV) in patients undergoing colorectal resection within an enhanced recovery after surgery programme. METHODS: Outcomes were audited prospectively in 1035 patients. Morbidity and mortality were compared with those predicted using the Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity, and a multivariable model was used to determine independent predictors of outcome. RESULTS: Postoperative morbidity was lower than predicted (observed to expected 0.68; P < 0.001). Independent predictors of delayed mobilization were ASA III-IV (P < 0.001) and advanced age (P = 0.025). Prolonged hospital stay was related to advanced age (P = 0.002), ASA III-IV (P < 0.001), male sex (P = 0.037) and rectal surgery (P < 0.001). Morbidity was related to ASA III-IV (P = 0.004), male sex (P = 0.023) and rectal surgery (P = 0.002). None of the factors predicted 30-day mortality. CONCLUSION: Age and nutritional status were not independent determinants of morbidity or mortality. Pre-existing co-morbidity was an independent predictor of several outcomes.