OBJECTIVE: We investigated the link between lipid-rich skeletal muscle, namely low-density muscle, and insulin resistance in Korea. RESEARCH DESIGN AND METHODS: Abdominal adipose tissue areas and midthigh skeletal muscle areas of 75 obese nondiabetic subjects (23 men, 52 women; mean age +/- SD, 41.9 +/- 14.1 years) were measured by computed tomography (CT). The midthigh skeletal muscle areas were subdivided into low-density muscle (0 to +30 Hounsfield units) and normal-density muscle (+31 to +100 Hounsfield units). The homeostasis model assessment (HOMA) score was calculated to assess whole-body insulin sensitivity. RESULTS: The abdominal visceral fat area and the midthigh low-density muscle area were found to be well correlated with the HOMA score (r = 0.471, P < 0.01 and r = 0.513, P < 0.01, respectively). The correlation between low-density muscle area and insulin resistance persisted after adjusting for BMI or total body fat mass (r = 0.451, P < 0.01 and r = 0.522, P < 0.01, respectively) and even after adjusting for abdominal visceral fat area (r = 0.399, P < 0.01). CONCLUSIONS: The midthigh low-density muscle area seems to be a reliable determinant of insulin resistance in Korean obese nondiabetic patients.