Objective: To compare two in situ ballistic lithotripters, the lithoclast and the electrokinetic lithotripter (EKL), both of which can be used through the newer small-bore ureteroscopes, for their ease of use, robustness, fragmentation time, adequacy of fragmentation and stone-free rate., Patients and Methods: Forty-six consecutive patients with ureteric stones refractory to treatment by extracorporeal shock wave lithotripsy were randomized to undergo fragmentation using the lithoclast (23 patients) or the EKL (23 patients). One patient was excluded from analysis in the EKL group. The adequacy of fragmentation was recorded, with the degree and significance of proximal migration for each device. After treatment patients were assessed by plain X-ray and the stone-free rate was determined., Results: The mean (median) initial stone burdens in the lithoclast and EKL groups were 69 (50) mm2 and 72 (52) mm2, respectively. The respective mean (median) procedure duration and fragmentation time were 54 (50) min and 90 (49) s in the lithoclast group, and 50 (42.5) min and 87 (52.5) s in the EKL group; the differences were not statistically significant. In four (14%) patients of each group there was significant proximal migration of the stones. The stones were completely fragmented in 17 of 23 (74%) patients in the lithoclast group and 19 of 22 (86%) in the EKL group. There was no fragmentation in one patient in each group. In the lithoclast and EKL groups, 20 of 23 (87%) and 17 of 22 (77%) were rendered stone-free, respectively (P > 0.5). The equipment failed on two occasions in each group., Conclusion: In this randomized trial there was no significant difference in the stone-free rate, procedure duration, fragmentation time, proximal stone migration rate and equipment failure between these in situ ballistic lithotripters.