Thumb rotation is an essential component of circumduction in order to achieve pulp to pulp contact. In order to evaluate opponensplasty a special device was developed to quantify thumb rotation. This new technique, utilizing a special jig to hold the hand and video analysis, is described. Twenty-seven healthy volunteers (12 female and 15 male) were tested to obtain normative data. Rotation of the thumb was measured as the difference in angle between the thumb in abduction and extension and maximal circumduction. Rotation angles varied from 70 to 110 degrees. No gender or right/left differences in angles of rotation could be detected. We conclude that comparing rotation of the noninjured hand to the injured hand in evaluating opponensplasties, can be used as an accurate measurement of thumb circumduction and opposition. The new, non-invasive technique presented here offers quantative data.