We evaluated the possible effects of a calcium entry blocking agent "verapamil" on new stone formation and/or regrowth of residual fragments after shock wave lithotripsy (SWL) during long-term follow-up (>30 months) and compared the results with the success rates of adequate fluid intake. A total of 70 patients treated with SWL were randomly divided into three different groups, in the first two of which the patients received different preventive measures with respect to stone recurrence and/or regrowth. While 25 patients received a calcium channel blocking agent, verapamil hydrochloride, beginning 3 days before SWL and continued 4 weeks after the procedure, an additional 25 patients were put in an enforced fluid intake program and the remaining 20 patients received no specific medication and/or measure apart from close follow-up. Patients were followed regularly with respect to the clearance/regrowth of the residual fragments and that of new stone formation during long-term follow-up (within a mean follow-up of 30.4 months). The overall stone recurrence rate was 14% (10/70). Of the patients who became stone free (12/25, 48%) in group I, only one patient (1/12, 8.3%) showed a new stone formation during long-term follow-up. The figure was 40% (4/10) in group II patients and 55% (5/9) in group III patients receiving no specific medication. Regarding the residual stone fragments (<5 mm) after SWL, again high fluid intake was found to be the most effective on stone regrowth rates (2/13, 15.3%). Patients treated with verapamil also had acceptable regrowth rates (3/15, 20%). Finally, verapamil treatment significantly improved the clearance of residual fragments; while 7 out of 15 patients with residual fragments passed these particles successfully, (46.5%) in this group; these figures were 46% (6/13) and 18% (2/13) in the remaining groups. Residual fragments located in lower calyces demonstrated a poor clearance rate with higher regrowth rates. Verapamil administration was found to be effective enough to limit the regrowth of residual fragments and also to facilitate residual fragment clearance after SWL. Patients receiving this medication seemed to pass the retained fragments easily in a shorter time than the others.