BACKGROUND: Given that a substantial number of daily activities take place in neighborhoods, a convenient and effective method for measuring the physical activity of individuals is needed. Therefore, we tested the validity and reliability of the Korean version of the Neighborhood Physical Activity Questionnaire (K-NPAQ), which was developed through translation and back-translation of the NPAQ. METHODS: The K-NPAQ was administered twice, with a 1-week interval, to participants in the study who were recruited at a health promotion center. We assessed energy expenditure and compliance using an accelerometer and an activity diary. The Kappa statistic and Spearman correlation coefficient were used to evaluate the test-retest reliability of the K-NPAQ, and the Spearman rank correlation was used to assess the validity. RESULTS: Of the 122 participants, 43 were excluded owing to a lack of compliance. The Kappa values for all items that were used to assess walking or cycling within or outside the neighborhood were >0.424; 0.251-0.902 for 5 items related to the purpose of the physical activity; 0.232-0.912 for most items related to the number of times and the duration for each types of physical activity. The total energy expenditure and the energy expenditure in the neighborhood were significantly correlated with the K-NPAQ and the accelerometer, with correlation coefficients of 0.192-0.264. CONCLUSION: The K-NPAQ is a valid and reliable tool for measuring physical activity in the neighborhood, and it can be used for individual education and counseling in order to augment physical activity in specific neighborhood environments.