The objective of this study was to evaluate the ability of age and the American Society of Anesthesiologists (ASA) score to act as clinical indicators and predict clinical adversity after abdominal surgery. We evaluated 2570 patients who underwent abdominal surgery. The data were collected in a prospective manner with an unbiased measurement of the baseline risk and endpoint criteria. Age > 60 years and/or an ASA score > 2 identified over 80% of the patients who had a prolonged stay in hospital, developed intraperitoneal sepsis, were admitted to the ICU or died. This effect was additive which implies a useful degree of independence between the two risk factors. Age and the ASA score are useful indicators of clinical adversity and resource utilization after abdominal surgery. Hence, they can be used to benchmark the outcome of abdominal surgery between institutions.