To evaluate the effects of old age and frailty on complication rates after surgery for pelvic organ prolapse. The American College of Surgeons' National Surgical Quality Improvement Program database was used to identify patients who underwent surgery for prolapse from 2010 to 2017. We compared our control group (45-64 years, index population) to those aged 65-79 years (elderly) and 80 years and older (very elderly). Frailty was assessed using the National Surgical Quality Improvement Program Modified Frailty Index-5. The primary outcome was the composite rate of serious complications and mortality. We analyzed 27,403 patients in the index population, 20,567 in the elderly group, and 3,088 in the very elderly group. The composite rate of serious complications in the index population was 4.5%, compared with 4.7% in the elderly group (odds ratio [OR] 1.0, 95% CI 0.9-1.1) and 9.0% in the very elderly group (OR 2.1, 95% CI 1.8-2.4). Compared with the index group, the very elderly group had notably elevated risks of cardiac complications (OR 11.9, 95% CI 6.2-23.0), stroke (OR 26.6, 95% CI 5.4-131.8), and mortality (OR 39.9, 95% CI 8.6-184.7). On multivariate logistic regression, the only age group independently associated with serious complications was the very elderly group (adjusted odds ratio [aOR] 2.01, 95% CI 1.8-2.3). The Modified Frailty Index-5 score was independently predictive of complications (aOR 1.4, 95% CI 1.1-2.0). Stratified analysis using interaction terms revealed the Modified Frailty Index-5 score to be predictive of complications in the elderly age group (aOR 2.5, 95% CI 1.3-4.6), but not in the very elderly group. Serious complications surrounding prolapse surgery increase substantially in the cohort of patients older than 80 years of age, independent of frailty and medical or surgical risk factors.