We treated 105 consecutive patients with bladder calculi by microexplosion lithotripsy, with a success rate of 100 per cent. The weight of the removed calculi averaged 18 gm., with a range of 2 to 305 gm. For the procedure spinal anesthesia was used in 78 patients, while general anesthesia was used in 24. Minor extraperitoneal bladder perforation occurred only once and it resolved spontaneously several days later. Presently, we consider microexplosion lithotripsy to be the treatment of first choice for bladder calculi.