Joint mobility i.e. flexibility, is generally considered a physical ability by which to coordinate movements. It is also known that keeping an adequate range of motion (ROM) of the spine is very important for executing smooth and safe exercises with aging. In previous studies, flexibility was evaluated on the basis of ROM of the trunk or lumbar spine during trunk flexion and extension, and changes in ROM with age have been widely reported. Although it has been pointed out that the thoracic and lumbar spine move in a different manner during flexion and extension, there has been no systematic study focusing particularly on ROM of the thoracic spine with age. The objective of the present study was to examine the effects of aging on ROM of both the thoracic and lumbar spine during trunk flexion and extension by evaluating kyphosis and lordosis while standing at rest. The subjects were 165 (male 81, female 84) healthy volunteers ranging in age from 11 to 92 yr, with no orthopedic problems and who did not perform regular intensive exercise. The subjects were asked to stand still to allow measurement of kyphosis and lordosis angles, and then to perform intentional thoracic spine flexion, maximal trunk flexion and maximal trunk extension. The movements were videotaped and analyzed by using a 2-dimensional analysis program (Frame-DIAS-2 V3, D.K.H., Tokyo.) ROM of the thoracic and lumbar spine during trunk flexion and extension was evaluated from the coordinates of three sets of newly designed markers. The present results showed that thoracic ROM during trunk extension decreased significantly with age for males. For females, a significant increase of kyphosis and a significant decrease of thoracic ROM during trunk extension with age was apparent. On the other hand, no significant effects of aging were observed in kyphosis for males and in thoracic ROM during trunk extension for females. In addition, a significant decrease of lumbar lordosis and ROM were confirmed for both males and females. From the results of this study, it is suggested that the effects of aging differ in the thoracic and lumbar spine, and it is considered that joint mobility of the thoracic spine and lumbar spine should be evaluated independently.