The modified triaxial goniometer was designed based on the gyroscopic concept. This device is capable of measuring the joint three-dimensional angular motion corresponding to a specific set of Eulerian angles. Since the angular measurement by this device is not sequence dependent, it is convenient to provide unique motion patterns of the joint from one position to another. The joint rotational axes are oriented based on identifiable bony landmarks which provide a convenient visualization of the anatomical motion involved. The error caused by the exoskeletal attachment of the instrument can be theoretically corrected. Considering all factors in joint functional evaluation, the triaxial goniometer is a useful and effective method to provide simple real time three-dimensional angular motion measurements.