Background. The aim of this study was to establish the incidence of abnormal ultrasonographic (US) fin dings of gallbladder (GB) in surgical patients with the prolonged stay in the intensive care unit (ICU) and to correlate these findings with the severity of illness. Methods. In the prospective study fifty-seven (57) adult surgical patients (male 66%; age 49±18 yr.) with the prolonged stay in ICU (>14 days) were analyzed. In all patients the US examination was performed on the 15th day of their stay in ICU. The presence of the following US findings was analyzed: GB wall thickening (?4 mm), biliary sludge, GB hydrops, striated GB wall and pericholecystitic fluid. The severity of illness was also evaluated on the 15th day of the stay in ICU using Simplified Acute Physiology Score (SAPS II). Results. At least one abnormal US finding was found in 36 (63%), patients with GB wall thickening in 32 (56%), biliary sludge in 23 (40%), pericholecystitic fluid in 9 (16%), hydrops of GB in 7 (12%), and striated GB wall in 4 (7%) cases, respectively. Two to five US findings were found in 20 (35%) patients, three to fi ve in 12 (21%), four to five in 10 (18%), while all five US findings were present in 4 (7%) cases. The pati ents with one and more US findings had significantly higher SAPS II than the patients who presented regu lar US findings of the GB (36±9 vs. 28±7; p < 0.01). The patients with two and more US findings had hig her SAPS II than those with one or none US criteria (40±8 vs. 29±6; p < 0.001), while the patients with three and more had higher SAPS II than those with two, one or none (41±8 vs. 31±9; p < 0.001). The patients with four or five US findings had higher SAPS II than those with three or less (42±11 vs. 31±6; p < 0.001) whi le the patients with all five had higher SAPS II than all others (45±10 vs. 32±9; p < 0.001). A significant po sitive correlation between the number of US findings and SAPS II was present (r = 0.57; p < 0.001). Conclusions. More than half of all surgical patients with the prolonged stay in ICU have GB abnormaliti es seen by ultrasonography; and it is in direct correlation with the severity of illness.