Few studies have examined the influence of marriage on health-related behavior in Asian populations. The present study examined the effect of marital status on smoking in Korea. Data from two rounds of a nationally representative survey (1999 and 2003) were analyzed (57,246 women and 52,769 men). Marital status-specific prevalence ratios for smoking were estimated using log binomial regression after adjusting for age, survey year, occupation and education level. Smoking prevalence declined with age for men, but rose for women. Smoking rates were higher for unmarried men and women compared to their married counterparts. However, the gap in smoking rates between unmarried and married women (especially younger women <45 years) was much greater than the gap between unmarried and married men. The study found that marital status had a stronger protective influence on smoking in women than men, which contrasts with the gender pattern reported previously in western studies. The findings suggest the influence of a culture which discourages married women from smoking, and "liberates" divorced women from cultural sanctions against smoking in marriage.