An ergonomic mouse accessory that allows the user to easily manipulate the control buttons of the mouse with a variety of hand positions and varying movements, thereby reducing or eliminating repetitive strain injuries and increasing accessibility to those unable to operate a standard mouse. In one embodiment a sleeve is positioned over the front of the mouse and a click stick is secured to the sleeve so that the lower end of the stick contacts the mouse button while the majority of the stick protrudes above the sleeve. Striking the stick produces a lever and fulcrum action, wherein the connection of the stick at the point of contact with the sleeve acts as a pivot point and causes the lower end of the stick to depress the mouse button. A spring means can be used to return the stick to the fully vertical position. Other embodiments include a cup that is attachable to a mouse button with a stick extending from the cup, and a plate embodiment that engages the mouse and permits the stick to manipulate the mouse buttons.