The main advantages of the Steffens lasso loop are its olive-tipped, 45 degrees-angled Tiemann guide, which allows easier and less traumatic passage above the ureteral stone, the tri-part lasso, which affords a better grasp of the stone, and the outlet for urine drainage. Between 1976 and 1986 we used this loop in 560 of 919 patients with distal ureteral stones. Immediate stone extraction was possible in 85.7% of the patients treated in 1986. Perforation of the ureter occurred in 2.3%, and 3% required ureterolithotomy. Our experience with this lasso loop has shown this instrument to be a valuable addition to other endourological methods.