OBJECTIVE To describe three cases of acute acalculous cholecystitis (AAC) in critically ill patients. METHODS Admission charts of critically ill patients who required advanced life support in the intensive care unit and fulfilled three or more of the following ultrasonographic or tomographic diagnostic criteria for AAC were reviewed: 1. Gallbladder wall thickness > 4 mm with an increase in its volume (vesicular hydrops), 2. Pericholecystic fluid, 3. Subserosal edema, 4. Sloughing of the mucosa, 5. Abscence of calculi. RESULTS Three men that met the criteria for AAC were identified from a total of 490 admission charts. The median age was 49 years, the average APACHE II at admission was 17 points. The median time in the ICU before development of AAC was 24 days. All patients had leukocytosis. The three cases were resolved by percutaneous cholecystostomy and external biliary drainage. CONCLUSIONS The incidence of AAC in our ICU is one s case per 160 admissions or 0.6%. Shock, use of vasopressor drugs, narcotics and mechanical ventilation with PEEP are frequent in patients who subsequently develop AAC. Percutaneous cholecystostomy with external biliary drainage constitutes a safe and definitive treatment when there is no gangrene of the gallbladder wall.