With an aging population, medical expenses for elderly patients are increasing rapidly. Frailty is currently considered an important issue in geriatrics. The purpose of this study was to investigate the effect of frailty on medical expenses in elderly Korean patients.Data were gathered from the 2008 and 2011 living profiles of older people surveys (from August 11, 2008 to February 20, 2012) and included 5303 community-living Korean men and women, aged 65 years or older. The five-item frailty index was comprised of items on weight loss, exhaustion, weak grip strength, slow walking speed, and low physical activity. Frailty data were extracted from the 2008 living profiles of older people survey, and out-of-pocket medical expenses data were extracted from the 2011 living profiles of older people survey. A generalized linear model was used to analyze the correlation between frailty and medical expenses after adjusting for sociodemographics, health behavior, and health status factors.Baseline frailty assessments grouped patients as robust (43.3%), prefrail (49.3%), and frail (7.4%). After adjusting for sociodemographics, health behavior, and health status variables, frailty was found to increase out-of-pocket medical expenses (robust: ref., prefrail: β=0.087 and P<0.001, frail: β=0.143 and P<0.001).Our findings suggested that frailty is an independent predictor of increasing medical expenses in community-dwelling elderly patients.