Upon coverage of a new drug by National Health Insurance in the Republic of Korea, the A-7 pricing is used as a reference for pharmaceutical benefit assessment. However, improvements need to be made regarding a specific formula currently used for the conversion of drug prices because the formula used to obtain the percentages is outdated and there is insufficient evidence on how the percentages were derived. In this study, the characteristics of 10 countries that have implemented external reference pricing and factors that affect drug prices such as profit margins for wholesalers and pharmacies, value-added tax (VAT), and rebates were examined with a focus on ex-factory price (EFP). In addition, we calculated EFP through conversion from each country's drug prices, compared EFP with the pharmacy purchase prices, and based on the above, drew implications for improving the foreign drug price reference values. Our results showed EFP to be publicly available in six countries (