sion, diabetes, malignancy, arthritis, cardiovascular and cerebrovascular diseases, smoking, and obesity increased the risk of ERdHP. To enhance the sustainability of labor in an aging society, more studies on ERdHP are needed. (J Occup Health 2015; 57: 28-38) Key words: Aging, Cox proportional hazard model, Early retirement, Gender, Korean longitudinal data Involuntary early retirement is a serious financial concern for workers and their families 1) . Beyond the individual level, early retirement contributes to social problems. Because most industrialized countries have an increased life expectancy and reduced birth rates, social concern has developed with regard to increasing labor force participation and decreasing involuntary retirement 2) . Various studies have indicated that worker retired early due to illness even though they needed to work to maintain their economic lives 3) . Illness also affects restarting work participation after retirement in old age 4) . Some studies have shown that chronic disease affects early retirement 4) . Furthermore, studies that used self-perceived health status to investigate the effect of illness on early retirement 5) suggest that selfperceived health is a very important factor in the retirement process 6) . In addition, it is important to identify specific diseases related to early retirement in order to reduce the risk of early retirement. For example, workers with psychological diseases such as depression show higher job turnover, low productivity, and eventually high retirement rates 7) . Lower physical functioning, working error, and limitations at work are predictors of early retirement, and these factors are linked to musculoskeletal disorder 8) . Nevertheless, few The aim of this study was to elucidate the effect of illness and unhealthy behavior on early retirement due to health problems (ERdHP) using Korean longitudinal data. Methods: This study used data collected from 3,508 subjects enrolled in the first to fourth phases of the Korean Longitudinal Study of Ageing (KLoSA). This study was conducted from 2006 to 2012 using structured questionnaires on retirement, morbidities, and health-related behaviors. We adopted the Cox proportional hazard model to investigate the effects of diagnosed disease and health-related behaviors on ERdHP. Results: Participants who smoked, were obese, or suffered from hypertension, diabetes, malignancy, heart disease, stroke, or arthritis had a significantly higher risk of health-related early retirement after adjustment for gender, age, and occupation. Further, risk factors such as lack of exercise, stroke, arthritis, obesity, and malignancy differentially affect early retirement by gender. Conclusions: This is the first study, that we are aware of, to examine the effect of illness and unhealthy behavior on ERdHP in Asia, using Korean longitudinal data. We found that hyperten-