Casts of 42 patients free from temporomandibular joint problems were mounted on an articulator in centric relation contact position. The movement of the horizontal axis of rotation was measured when the casts were moved from centric relation contact position to the intercuspal position. Measurements of the vertical and horizontal movements of the incisal pin were also made during this movement. There was a highly significant correlation between the movement of the horizontal axis in the horizontal plane and the ratio of vertical to horizontal movement as measured at the incisal pin. The greater this ratio was, the smaller the horizontal movement of the axis was; the smaller the ratio (the larger the horizontal component) was, the larger was the horizontal movement of the axis. The clinical implications are discussed.