OBJECTIVES: To confirm whether price premiums rewarded for new drugs in Japan  were justified by pharmacoecomic analysis. METHODS: We systematically reviewed the economic evaluation studies of new drugs launched in Japan between April 2000 and March 2010 that were priced by the similar drug comparison method, in which prices are set by comparison with prices of similar drugs. The “Ichushi” and PubMed databases were used to search the published articles. RESULTS: 220 drugs were priced by the similar drug comparison methods during the 10-year period. In total, 22 published articles (16 drugs) were identified: 3 CUAs, 18 CEAs, and 1 CMA. In 10 out of 22 articles, only drug costs were included in the cost estimation. There was a wide range of variation in outcome measures utilized and life-years were only applied in 2 of 18 CEAs. The most common outcome used was the proportion of patients who achieved target clinical results. Incremental analysis was performed in 11 articles; however, the threshold for decision making was mentioned in only 3 of these articles, even though 3 other studies did not take into account because the results were dominant. While price premiums were rewarded to all new drugs reviewed, only 8 of 16 drugs were cost-effective, 5 drugs were not cost-effective, and the cost-effectiveness of 3 drugs was uncertain or inconsistent between articles. CONCLUSIONS: Our literature review indicated only halves of the drugs with premiums were reported to be cost-effective. However, cost-effectiveness of the drugs could not be determined objectively because of a wide range of variation in methods such as outcome measures and cost calculation. To utilize economic evaluations in policy making and clinical practice in Japan, formulation of methodological standards is necessary to ensure consistency among studies.