Abstract. Our objective was to compare the effectiveness of percutaneous cholecystostomy (PC) vs conservative treatment (CO) in high-risk patients with acute cholecystitis. The study was randomized and comprised 123 high-risk patients with acute cholecystitis. All patients fulfilled the ultrasonographic criteria of acute inflammation and had an APACHE II score 12. Percutaneous cholecystostomy guided by US or CT was successful in 60 of 63 patients (95.2%) who comprised the PC group. Sixty patients were conservatively treated (CO group). One patient died after unsuccessful PC (1.6%). Resolution of symptoms occurred in 54 of 63 patients (86%). Eleven patients (17.5%) died either of ongoing sepsis (n=6) or severe underlying disease (n=5) within 30days. Seven patients (11%) were operated on because of persisting symptoms (n=3), catheter dislodgment (n=3), or unsuccessful PC (n=1). Cholecystolithotripsy was performed in 5 patients (8%). Elective surgery was performed in 9 cases (14%). No further treatment was needed in 32 patients (51%). In the CO group, 52 patients (87%) fully recovered and 8 patients (13%) died of ongoing sepsis within 30days. All successfully treated patients showed clinical improvement during the first 3days of treatment. Percutaneous cholecystostomy in high-risk patients with acute cholecystitis did not decrease mortality in relation to conservative treatment. Percutaneous cholecystostomy might be suggested to patients not presenting clinical improvement following 3days of conservative treatment, to critically ill intensive care unit patients, or to candidates for percutaneous cholecystolithotripsy.