The OrthoMouse represents a quantum leap in the design of hand held computer input devices and not a band aid on pre-existing concepts. It has been conceived and developed by a medical doctor to completely respect the anatomy and function of the human hand and to specifically 'do no harm'. It finally seriously addresses the pandemic of Repetitive Strain Injuries (RSI) resulting from extensive use of tools that do not fully respect the anatomy and function of the hand that uses them.