Introduction: With enactment of the 1995 Health Promotion Act, the Korean government has developed numerous antismoking policies, including smoke-free buildings and zones, a public media campaign, and tobacco taxation. The present study examined whether governmental antismoking policy during the past decade was associated with reduced socioeconomic differentials in cigarette smoking in South Korea. Methods: Data from 99,980 men and 105,193 women aged 25-64 years were analyzed from four rounds of Social Statistical Surveys of Korea between 1995 and 2006. Socioeconomic position (SEP) indicators were education, occupational class, employment status, and household income. Age-adjusted prevalence of smoking was calculated. Prevalence ratios and the relative index of inequality (RII) were estimated using log-binomial regression analysis. Results: Absolute socioeconomic differentials in age-adjusted prevalence of smoking increased between 1995 and 2006. Increases were found in both men and women. Prevalence ratios and RIIs also showed widening relative inequalities in smoking in all four SEP indicators in men. For women, increases in RIIs for education and income were statistically significant. The magnitude of change in prevalence ratios and RIIs by SEP indicators between 1999 and 2003 was statistically significant, whereas the difference between 2003 and 2006 was not. Discussion: Despite reducing overall cigarette smoking rates in males, the governmental antismoking policies of South Korea did not reduce socioeconomic inequalities in smoking in both genders. However, the recent tobacco taxation policy is likely to dampen the ever-increasing trends in smoking inequalities. More progressive antismoking policies to reduce socioeconomic inequalities in smoking are warranted in South Korea.