Kangwha Cohort Study was established in March 1985 among residents of Kangwha County in Republic of Korea who were 55 years or older in February 1985. The purpose of this study was to prospectively examine the association of body mass index (BMI) with mortality from all causes and specific causes such as cancers, vascular diseases, and respiratory diseases in Korean older people. A total of 6,166 people (2,636 men and 3,530 women) were defined as a study population. Data on deaths and their causes from 1 January 1992 to 31 December 2008 were confirmed by national death records from the National Statistical Office of Korea. Data on those who died from March 1985 to 31 December 1991 were collected either through calls or visits of trained surveyors twice a year, or from records of burial and death certificates at local administrative branch offices in each study region.