This study aimed to identify the changes in the list of drugs covered by national health insurance(NHI) after the introduction of positive list system (PLS) in Korea in December, 2006. Six-year (pre-policy:2004-2006, post-policy:2007-2009) lists of the NHI reimbursable drugs filed from Health Insurance Review and Assessment Service (HIRA) were analyzed. The total number of listed drugs as well as drug ingredients, and the average number of listed drugs per manufacturer decreased annually after the introduction of PLS. More than 8,000 drugs were delisted in the year 2007 right after the policy change. Prescription-only drugs occupied more than 85% of NHI listed drugs. The percentage of oral type of listed drugs has been increased to more than 60% after the policy change. Korean pharmaceutical manufacturers occupied more than 90% of listed drugs than multinational firms. The gap between Korean and foreign manufacturer in terms of the average number of newly listed drugs per manufacturer in each year has decreased two years after the PLS (Korean 7.7 vs. foreign 6.3 in 2009) as the price negotiation power of foreign firms has increased. The total number of listed drugs is expected to decrease in the future as the Korean government makes an effort to delist the unnecessary drugs that do not show cost-effectiveness.