Abstract: A wrist mechanism for a robotic manipulator having kinematically zero length and mutually orthogonal unlimited joints is provided. The wrist mechanism provides access to any reachable point from any arbitrary direction. The wrist mechanism includes an intermediate joint created by two parallelogram four-bar linkages operating in parallel. Each of the four bar linkages include two side bars, a fixed bar and a coupler bar. The coupler bars extend to support a last link of the wrist mechanism which holds an end effector. The kinematic lengths of the side bars are less than the kinematic lengths of the fixed and coupler bars. The side bars of the first parallelogram four-bar linkage are fixed out of phase with respect to the side bars of the second parallelogram four-bar linkage. Also, the side bars of both parallelogram four-bar linkages occupy multiple planes which, along with the kinematic lengths of all the linkage bars, allows for unlimited rotation and zero dwell time.