This study explores the effectiveness of bilingual Korean classes for beginner-level Korean language learners (international students) at W University in Korea. This study used various data sources to achieve this research purpose. Data collection consisted of 1) an end-of-semester survey and 2) Korean language learners and Korean teachers' interviews. The results are followed. First, bilingual Korean classes for beginner Korean language learners were effective. Second, Korean teachers used bilingual Korean instruction during the course when teachers needed grammar descriptions, sentence semantic descriptions, and grammatical errors. Third, beginner-level Korean language learners responded that they had positive perceptions and attitudes towards bilingual Korean classes. Also, Korean language learners were generally satisfied with bilingual Korean courses. Based on these findings, several suggestions for bilingual Korean courses are provided.