The number of patients with geriatric diseases will rapidly increase in our aging society. Geriatric diseases tend to progress chronically and disturb the daily activity of the elderly patients. Care for the elderly patients requires a great deal of manpower. The prevention and treatment of geriatric disease are urgent issues that must be addressed. A comprehensive longitudinal study of aging and geriatric disease was started at the National Institute for Longevity Sciences (NILS) in 1997. The participants of the NILS longitudinal study of aging (NILS-LSA) were 2,267 men and women from a local community population. The participants are examined at the NILS and followed up every two years. An outline of the system and examinations of the NILS-LSA is shown. The latest results from the NILS-LSA research including geriatric disease-related genotypes and risk factors for mild cognitive impairment (MCI) are also presented.