OBJECTIVE:This study aimed to evaluate the validity and reliability of the Japanese version of the Neuropathic Pain Symptom Inventory (NPSI-J). DESIGN:Cross-sectional study design. SUBJECTS AND METHODS:The original Neuropathic Pain Symptom Inventory (NPSI) was translated into Japanese according to published guidelines. Subsequently, an observational study of 60 Japanese patients suffering from neuropathic pain was performed to evaluate the validity and reliability of the NPSI-J. RESULTS:The NPSI-J exhibited a statistically significant correlation with pain intensity (Numerical Rating Scale). The Cronbach alpha value for Likert items was 0.86. Using the test-retest analysis method, the intraclass correlation coefficient between the two scores was 0.81. Factor analysis revealed that the main component of NPSI-J comprised three determinative factors. CONCLUSIONS:The NPSI-J is a reliable and valid pain assessment tool.