Abstract: A medical retrieval basket having superelastic metallic alloy wires attached to the distal end of an inner elongated member tube for percutaneously capturing and removing calculi from a cavity or duct of a patient. The basket comprises kink-resistant superelastic metallic alloy wires such as nitinol which forms a bulbous shape for capturing calculi therein. The ends of the superelastic wires of the basket extend through the passageway of the inner elongated member tube and are attached to the proximal end of the tube. An outer elongated member tube is percutaneously inserted into the biliary or urinary system. The inner member tube is inserted through the outer member tube into a duct, cavity or organ of the patient. The distal ends of both the inner and outer member tubes have a predetermined longitudinal curvature for controlling the positioning of the basket and the tubes within the patient.