Electrohydraulic lithotripsy (EHL) is an effective means of intracorporeal fragmentation of symptomatic ureteral calculi, and the recent development of 3.OF and 1.9F EHL probes has extended the safe use of this modality in the upper urinary tract. Over the last 10 months, 30 patients have undergone flexible ureterorenoscopy and lithotripsy with either a 3.0F or a 1.9F EHL probe for mid or upper ureteral or renal calculi. All cases of intrarenal lithotripsy were performed for ureteral stones or stone fragments that migrated into the renal collecting system during manipulation. Stones ranged in size from 5 to 15 mm with an average of 8 mm. In 27 cases (90%), the stones were fragmented using a power setting between 60 and 90 V. No instances of ureteral or renal mucosal damage were noted. All patients underwent intravenous urograms 1 month after treatment, with no evidence of ureteral extravasation or stricture being found. Procedures were performed as day surgery cases in 87% of patients. Intracorporeal electrohydraulic lithotripsy appears to be a safe and effective modality for fragmentation or ureteral calculi. Moreover, the 1.9F EHL probe ensures improved irrigant flow through the flexible ureterorenoscope, which maintains adequate visibility. In addition, this probe can supply adequate power to fragment even calcium oxalate monohydrate calculi. We believe that the continued development of smaller EHL probes will provide a safe, effective, and significantly cheaper alternative to laser lithotripsy for the intracorporeal fragmentation of ureteral and renal calculi.