A new technique for quantifying wrist circumduction was developed and evaluated using a biaxial flexible electrogoniometer. The reliability and validity of the electrogoniometer for the measurement of wrist motion were first tested, and then the device was applied clinically. The reliability tests demonstrated sufficient accuracy of the device. Also, validity of the measurement was recognized because the tests simulating wrist circumduction and cineradiography revealed that it could accurately detect the angle between the long axis of the forearm and the third metacarpal bone. Lissajous's figure was made from the two channel signals of the electrogoniometer, and the Range of Motion index for wrist circumduction was newly defined from this figure. This index represents the dynamic range of motion of wrist circumduction. Ten healthy men (ages 19-31 years) and three patients with wrist disorders were studied. In the patients, Lissajous's figures and Range of Motion indexes were markedly different from the healthy. In addition to this study, preliminary data on the 'velocity-angle loci' of healthy men during wrist circumduction were obtained for further detailed analysis.