The International Nonproprietary Name (INN), nomenclature for pharmaceutical substances designated by WHO, is known to reduce confusion arising from different names of generic drugs, therefore is being widely used in countries such as France and Japan. It is allowed to name generic drugs with either brand names or INN according to the pharmaceutical affairs act of South Korea. In our study, we aim to investigate the status of INN use in drug product names and identify the factors affecting use of INN in South Korea. We constructed an integrated data using data provided by Health Insurance Review and Assessment (HIRA) (a full list of covered drugs, accumulated drug price, and drug production and import performances) and by pharmaceutical affairs act (regulations on classification of medicines). Among the drugs covered in South Korea as of January 1st, 2024, oral drugs with single active ingredient were included and stratified into two categories in respect to whether their names included INN (i.e. INN-labeled). The proportions of INN-labeled drugs were examined based on their active pharmaceutical ingredient (API), classification of medicinal properties, the order of reimbursement entry within the API, and production/import performances of their manufacturers. Ordinal logistic regression and Spearman's chi-squared test was performed to test the statistical significance in the trend or difference across groups. Out of 13,667 covered drugs, 8.96% (N=1,224) were INN-labeled. Each API had an average of 16.98 drugs, and APIs with the largest number of drug products were Rosuvastatin (328 products), followed by Donepezil (293 products) and Atorvastatin (272 products). Drugs were more likely to be INN-labeled when its order of reimbursement entry was later within the same API (estimated coefficient: 0.36, p<0.05) and when its manufacturer had less production or import performances(x2 = 25.06, p<0.05). By medicinal properties, the number of active ingredients in each classification did not exhibit a significant correlation with the proportion of INN-labeled drugs (Spearman's correlation coefficient: -0.15, p=0.18). Among numerous oral drugs covered by the national health insurance of South Korea, only a small proportion was INN-labeled. Drugs with later reimbursement entry order and produced by manufacturers with low performance were more likely to be INN-labeled. Guidance on the use of INN would help the expansion of INN usage, which could aid the safe use of generic drugs.