PURPOSE: To evaluate the usefulness of spiral CT in the measurement of lung volumes. MATERIALS AND METHODS: Fifteen healthy volunteers were studied by both spirometer and spiral CT at full inspiration and expiration inorder to correlate their results, including total lung capacity (TLC), vital capacity (VC) and residual volume(RV). 3-D images were reconstructed from spiral CT, and we measured lung volumes at a corresponding CT window range ; their volumes were compared with the pulmonary function test (paired t-test). RESULTS: The window range corresponding to TLC was from -1000HU to -150HU (p=0.279, r=0.986), and for VC from -910HU to -800HU (p=0.366,r=0.954) in full-inspiratory CT. The optimal window range for RV in full-expiratory CT was from -1000HU to -450HU (p=0.757, r=0.777), and TLC-VC in full-inspiratory CT was also calculated (p=0.843, r=0.847). CONCLUSION: Spiral CT at full inspiration can used to lung volumes such as TLC, VC and RV.