The KMIC Study was established to estimate the prevalence and patterns of major cardiovascular disease (CVD) risk factors among South Korean adults, to inform national prevention strategies. The cohort consisted of over 183,000 participants aged 35 to 59 years, including around 115,000 men and 68,000 women who were all eligible insured workers. Participants were recruited from across South Korea through mandatory health examinations conducted by the KMIC at 416 hospitals, with data collected during two examination cycles in 1990 and 1992. Follow-up on longer-term outcomes was tracked via passive linkage to national mortality records.