Electrohydraulic lithotripsy (EHL) of ureteral calculi has proved to be an effective and relatively inexpensive method of intracorporeal lithotripsy. However, the potential for significant ureteral injury is an everpresent concern with conventional EHL. The electromechanical impactor (EMI), an innovative modification of a standard EHL probe, has been shown in initial investigations to be capable of fragmenting urinary calculi with a greater margin of safety. Herein, we describe our preliminary experience with this new device in 23 patients with ureteral calculi. In nine patients selected to undergo EMI treatment, the device could not be employed because of either inability to access the stone with the large endoscope required (six cases) or device malfunction (three cases). Among the patients in whom the EMI was used, five required an additional modality of intracorporeal lithotripsy to complete stone fragmentation. In the remaining nine patients, stone fragmentation was achieved with the EMI as the sole modality of lithotripsy, for an overall success rate of 39% (9/23). There were no complications directly related to use of the EMI as noted endoscopically or on postoperative imaging. The EMI appears to be a safe device for intracorporeal lithotripsy. Its application to a large population of patients with ureteral stones may be limited by the probe size (5F), which precludes its use with the smaller rigid and flexible ureteroscopes.