Over the course of 18 months, 160 patients underwent endoscopic holmium:YAG laser surgery at our institution for the treatment of urolithiasis, After appropriate consent had been obtained, 127 patients were treated for ureteral calculi, 18 for renal calculi, and 15 for large bladder stones. All procedures were performed using the VersaPulse combination holmium:YAG/Nd:YAG laser by Coherent Inc., and all were done endoscopically using video guidance. Of the 16 patients treated percutaneously for renal calculi, 5 were rendered stone free (mean stone size 3.5 cm), Two patients with renal calculi were treated in a retrograde fashion, One had a l-cm stone in an upper-pole calix with a narrow infundibulum, while the other had a stone just proximal to the ureteropelvic junction. Both patients were rendered stone free. Of the 127 patients with ureteral calculi, 46 had stents placed after fragmentation of their stones. To date, 123 patients in this group (97%) are free of stones. All 15 patients with bladder calculi had complete fragmentation of their stones. The Ho:YAG laser is effective and versatile in the treatment of urolithiasis.