Introduction It has been studied that long working hours is associated with health problem such as coronary heart disease (CHD) and stroke. The aim of this study was to investigate the association between long working hours and risk of CHD and between long working hours and risk of stroke estimated by using Jee’s health risk appraisal model.

Materials and methods We analysed data from Korean National Health Nutrition Examination Survey 2007–2013. The participants for this study was 13,799, who were current worker and in 30 to 60 years old of age with complete data. Jee’s health risk appraisal model, modified form of Framingham equation model, was developed to properly estimate risk of CHD and risk of stroke in Korean population. The individuals’ risk for CHD and stroke was determined using Jee’s health risk appraisal model, and high risk group was defined as upper 10 percent of estimated risk. Multiple logistic regression was conducted to study the association between working hours and 10-year risk for CHD and stroke estimated by Jee’s health risk appraisal model.

Results Average risk of CHD predicted by Jee’s model was 1.11% and 0.26% in men and women. Average risk of stroke was 1.97% and 1.45% in men and women. Comparing between those who work 40 hours per week and those who work over 80 hours per week, the odds ratio (OR) for high risk for coronary heart disease was 1.76 (95% CI = 1.23–2.52) in men and 1.63 (95% CI = 1.03–2.58) in women. The OR for high risk for stroke was 2.32 (95% CI = 1.46–3.69) in women.

Conclusion Long working hours are significantly associated with risk of CHD in both sexes and associated with risk of stroke in female. This study suggests that the proper management of working hours to reduce health risk in the Korean population.