Urinary incontinence (UI) is very common in the elderly and has personal and social implications. Many authors have pointed out the necessity to analyze UI in correlation with the overall quality of aging, to better understand this syndrome and define measures for its prevention and treatment. In the present study, we addressed this problem by analyzing the UI correlation with frailty, which has emerged in the last decade as the geriatric syndrome correlated with individual homeostatic capacity and then as the basis of the age-related physical decline. In addition, the monitoring of our sample for a long period allowed us to estimate the prognostic significance of UI by analyzing the correlation between UI and mortality. The analysis was performed in a large sample that included numerous ultra-nonagenarians, a population segment that is still poorly known for UI and other geriatric parameters. We found a strict correlation between UI and frailty, suggesting that UI is correlated to the homeostatic and physiological decline leading to frailty. In addition, we found that UI is an independent mortality risk factor in ultra-nonagenarians, suggesting that the neurological sensitivity needed to be continent is lost very soon when the frailty associated physiological decline begins. On the whole, our study suggests that UI is a marker of frailty and that UI patients should be monitored and, in case, treated in a timely manner to avoid, or to limit, the effects of frailty such as malnutrition, falls, and the consequent accumulation of disabilities.