The aim of the study was to establish the efficiency of cholesterol gallstone dissolution with methyl tert-butyl ether in a large group of patients and to compare the results of patients treated manually by a nurse or using an automatic pump. Gallbladder puncture was successful in 228 patients (99%). After 9 hr, 211 patients (91%) were stone-free; 144 (68%) of them left the hospital on the fourth day. In radiolucent stones not isodense with bile on a CT scan, dissolution rate decreased by 10%, treatment time was prolonged by 40%. Forty-two of the 228 patients were selected for the hand-syringed group, 42 patients, who matched these patients in stone size and number, were treated with an automatic pump (Baxter). Stone burden in matched pairs was comparable. Stones dissolved in 96% of the patients in both groups. Sludge remained in the gallbladder in 52% after manual treatment and 60% after automatic therapy. Side effects were identical in both groups. None of the side effects were pump-related. Automatic therapy reduced the time needed by the nurse to treat each patient by 70%.