OBJECTIVES: In Korea, Positive List System(PLS) was introduced as a drug listing system in Jan 2007. This study aimed to comparatively analyze the impact of the PLS introduction on the listing of incrementally modified drugs(IMD) and new drugs(ND). METHODS: Database for new drug coverage assessment was established based on selective drug listing assessment data from HIRA website and MOHW reference publications. They analyzed the two-year drug listing data submitted to the Drug Review and Evaluation Committee (2007.1.-2008.12) since the introduction of PLS. SAS version 9.1 was used for descriptive analysis and logistic regression in statistical analysis. RESULTS: After the introduction of PLS, success rate of coverage decision was 74.6% and 50.6% for IMD and ND, respectively; for drug price agreement rate, 73.6% and 85.0%; for final drug listing rate, 54.9% and 43.0%, placing IMD higher than ND. Time to coverage decision for IMD and ND was 109.0days and 155.7days, respectively; time to drug listing was 192.9days and 260.0days, respectively, indicating much shorter time to decision and listing for IMD than general ND. The final listing rate was 52.1% for multinational pharmaceutical companies while being 48.6% for domestic drug makers. The factors having the largest influence on insurance listing were cost-effectiveness for IMD and financial impact for ND. CONCLUSIONS: The introduction of PLS resulted in higher coverage rate and shorter time to final listing for IMD compared to ND. The factors affecting the insurance listing differed between IMD and MD, with cost-effectiveness being the major factor for IMD.