Introduction Surgeons are increasingly performing surgery on older patients. There are currently no tools specifically for risk prediction in this group. The aim of this study was to review general surgical operations carried out on patients aged over 90 years and their outcome, before comparing these with predictors of morbidity and mortality. Methods A retrospective review was carried out at our district general hospital of all general surgery patients aged over 90 years who underwent a general surgical operation over a period of 14 years. Information collected included demographics, details of procedures, P-POSSUM (Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity), complications and outcomes. Results A total of 119 procedures were carried out, 72 involving entry into the peritoneal cavity. Overall, 14 patients (12%) died within 30 days and 34 (29%) died within one year. Postoperative complications included infection (56%), renal failure (24%), need for transfusion (17%) and readmission within 30 days (11%). Logistical regression analysis showed that the P-POSSUM correlated well with observed mortality and infection was a significant predictor of in-hospital mortality (p=0.003). Conclusions The P-POSSUM correlates significantly with outcome and should be used when planning major elective or emergency surgery in patients over 90 years of age. Infective complications appear to be a significant predictor of postoperative mortality. This study supports operative intervention as an option in this extreme age group but we emphasise the importance of appropriate patient selection and judicious clinical care.