In a recent in vitro study, mechanical vibration was shown to facilitate, considerably, both the passing of a basket catheter beyond an artificial ureteral stone as well as the extraction of a calculus. Therefore, a device by which vibration can be transmitted to the basket of a modified stone extractor was developed for clinical application. The basket moves to and fro with an amplitude of 2-4 mm and a frequency of 40-60 Hz. An experimental follow-up study was performed in dogs to find out whether the vibration procedure as such induced injuries to the ureters. Modified stone extractors were passed up bilaterally into the ureters of 11 dogs. Vibration was applied in a standardized manner to one side, the other non-vibrated side served as a control. Postoperatively, 5 dogs were followed during 4-5 weeks with repeated urographies. Specimens of the ureters were examined microscopically when the dogs were sacrificed. No complications which could be ascribed to the vibration procedure as such were observed. The vibration technique was tried also in a pilot study comprising 14 patients with distal ureteral stones; in 9 patients, the stones were successfully extracted. Of the remaining 5 patients in whom the stone extraction failed, 3 passed the stone spontaneously and in 2 ureterolithotomies were performed. No complications were encountered.