Diagnostic and rehabilitative assessments of hand function commonly omit measurement of twisting strength even though many activities of daily living require turning handles, lids, and objects of many sizes. A simple device to quantify twisting strength was designed and constructed to establish normative data and test hypotheses about hand function. The instrument is easy to use and includes an electronic torsional load cell and disks of several sizes. Tests were conducted on the dominant and nondominant hands of 64 normal subjects and 13 arthritic patients with arthritis of the thumb carpometacarpal joint. Hands were tested with disks ranging in diameter from . A three-way repeated measures analysis showed that gender , handedness , and disk size had significant effects. There was no difference between radial and ulnar deviation strengths . The arthritic group had significantly reduced strength . Nine subjects were tested twice, with between tests: no differences occurred between the first and second testing . The ability to distinguish the test groups with reproducible results proves that the device fulfills all basic requirements; continued testing and development are warranted.