Thirty patients (23 women, 7 men, mean age 53 [24-77] years) with symptomatic radiolucent gallbladder stones were treated by litholysis with methyl tert-butyl ether (MTBE), introduced through a catheter inserted into the gallbladder either by the percutaneous-transhepatic route (n = 19) or the transpapillary route (n = 11). Correct placing of the catheter was more frequently successful by the percutaneous-transhepatic route than the transpapillary one (90 vs 73%). The duration of lysis (median: 7 h and 8 h, respectively) and the proportion of stones which were completely dissolved immediately after lysis (53 vs 55%) were similar in both groups. Supplemented by subsequent oral therapy, the success rate at 6 months was higher in the percutaneous-transhepatic group (83 vs 64%), however, recurrences were more frequent. In the percutaneous-transhepatic group there was one case of gall-bladder leak and one catheter dislocation, and in the transpapillary group there was one case of pancreatitis, one of induction of ether anaesthesia and one pulmonary embolism. MTBE lysis is a relatively speedy and effective mode of non-operative therapy for gall-bladder stones. The percutaneous-transhepatic method is suitable for younger patients with a normal gall-bladder. The transpapillary procedure is preferable for older patients, and also when gall-bladder puncture proves difficult or when there is concurrent choledocholithiasis.