The purpose of this study is to identify key factors that determine a person's decision to seek treatment from traditional Korean medicine (TKM) instead of conventional medicine through analysis of nationally representative data from Korea, where a dual healthcare system exists. The analysis is based on episodic data from the 2008 and 2009 Korea Health Panel. The main dependent variable is the selection between TKM and conventional medicine. We used a multiple logistic regression model to identify the determinants of TKM while controlling for clustered error. Approximately 5% of all doctor's visits were characterized as TKM services. Urban residents were 1.441 times more likely to use TKM than rural residents (P = 0.001). The probability of choosing TKM over conventional medicine for a range of conditions compared to the reference condition (gastrointestinal disease) was as follows: circulatory system diseases (OR 5.267, P < 0.001), nervous system diseases (OR 12.054, P < 0.001), musculoskeletal system diseases (OR 20.579, P < 0.001), and neoplasms (OR 0.209, P = 0.004). Certain diseases are significantly more likely to be treated by TKM than by conventional medicine. This suggests that many people view TKM as being additionally effective for specific diseases, particularly musculoskeletal disorders.