BACKGROUND America's aging population has led to an increase in the number of elderly patients necessitating emergency general surgery. Previous studies have demonstrated that increased frailty is a predictor of outcomes in medicine and surgical patients. We hypothesized that use of a modification of the Canadian Study of Health and Aging Frailty Index would be a predictor of morbidity and mortality in patients older than 60 years undergoing emergency general surgery. METHODS Data were obtained from the National Surgical Quality Improvement Program Participant Use Files database in compliance with the National Surgical Quality Improvement Program Data Use Agreement. We selected all emergency cases in patients older than 60 years performed by general surgeons from 2005 to 2009. The effect of increasing frailty on multiple outcomes including wound infection, wound occurrence, any infection, any occurrence, and mortality was then evaluated. RESULTS Total sample size was 35,334 patients. As the modified frailty index increased, associated increases occurred in wound infection, wound occurrence, any infection, any occurrence, and mortality. Logistic regression of multiple variables demonstrated that the frailty index was associated with increased mortality with an odds ratio of 11.70 (p < 0.001). CONCLUSION Frailty index is an important predictive variable in emergency general surgery patients older than 60 years. The modified frailty index can be used to evaluate risk of both morbidity and mortality in these patients. Frailty index will be a valuable preoperative risk assessment tool for the acute care surgeon. LEVEL OF EVIDENCE Prognostic study, level II.