Abstract: A hydraulic shape memory alloy actuator is provided comprising a uniaxial shape memory alloy wire constructed of Nitinol. The actuator utilizes a pair of hydraulic cylinders in fluid communication with each other, each cylinder containing a hydraulic piston. The first hydraulic piston is moved from a first position to a second position when the wire, connected at one end to the piston and its other to a fixed point, changes from a martensitic to an austenitic state upon heating. The second hydraulic piston responds to the movement of the first hydraulic piston by moving from a rest position to an operating position. Upon cooling the wire to change it from the austenitic state back to the martensitic state, the first piston returns to its original position, with a biasing means being provided to return the second piston to its rest position.