[Purpose] The purpose of this study was to evaluate the correlation between the lumbar lordosis curve (LLC) and temperature differences of the lower extremity regions in lumbar herniated nucleus pulposus (L-HNP) cases. [Subjects] We divided the study subjects into patients with L-HNP (n=15) and normal persons (n=15). [Methods] Both the L-HNP group and control group were measured for LLC and temperature differences of the lower extremity regions by X-ray and digital infrared thermal imaging (DITI). [Results] The LLC and temperature differences of the lower extremity regions of the L-HNP group were significantly different from the control group. The LLC and temperature differences of the lower extremity regions of the L-HNP group showed strong positive correlations. [Conclusion] We found that as the LLC decreased, the difference in the temperature of the lower extremity regions in the L-HNP cases increased.