Intraoperative ultrasonography was performed in 24 patients with intrarenal pelvis or with recurrent or multiple stones. The stones were located by a 22 or 25 gauge needle, manually introduced under ultrasonography: they were then extracted through a small incision performed along the tract of the exploratory needle. This preliminary experience has shown that the real time B-mode intraoperative ultrasound can provide valuable results in urologic surgery.