Background: Frailty is related to adverse outcomes in the elderly. We aimed to validate established frailty criteria for community-dwelling Korean elderly. We also developed and validated a new frailty index based on a multidimensional model. Methods: We studied 693 participants of the Korean Longitudinal Study on Health and Aging (KLoSHA). We developed a new frailty index (KLoSHA Frailty Index, KFI) and compared predictability of the index with established frailty criteria from the Cardiovascular Health Study (CHS) and Study of Osteoporotic Fracture (SOF). Mortality, hospitalization, and functional decline were evaluated. Results: The criteria from SOF, CHS and KFI correlated with each other, with a Spearman`s coefficient from -0.003 to 0.487. During the follow-up period (5.6±0.9 years), 97 (14.0%) died. Frailty statuses from the CHS index and KFI (c-index: 0.596 and 0.713, respectably; p<0.001, better for KFI) were related to mortality but were not related to mortality using the SOF. The KFI showed better predictability for following functional decline than CHS index (AUC of ROC: 0.937 for KFI and 0.704 for CHS index, p=0.001); However, the SOF index did not have predictability for following functional decline. Frailty from the KFI (HR=2.13, 95% CI 1.04-4.35) and CHS criteria (HR=2.24, 95% CI 1.05-4.76) were significantly correlated with hospitalization. In contrast, frailty by the SOF index was not significantly correlated with hospitalization (HR=1.43, 95% CI 0.68-3.01). Conclusions: A novel frailty index (KFI), can be derived from geriatric assessment data, is a useful and valid criterion for the evaluation and prediction of frailty in the Korean elderly population.