An orthopedic computer mouse including a flat base substantially shaped as a parallelogram, the mouse having a central region substantially shaped as a hemispheric dome, separated from a lateral recess wherein the thumb is fitted by a projection feature that ensures the pincer position assumed by the hand of the user, and containing a standard-sized body which houses control buttons electronic components and the motion sensing means. An elongating attachment supports the proximal region of the hand of the user and presents a projection feature. Both elements are attachable to the body by mutually cooperating latching elements. The elongating attachments and the projection features are manufactured to accommodate a wide range of hand sizes.