Antibiotic resistance among Gram-negative rods (GNRs) causing hospital-acquired infections poses a threat, particularly to intensive care unit (ICU) patients. This study was undertaken in order to achieve the following: to detect the frequency of GNRs isolated from coronary and surgical ICUs at the Institute of Cardiology, Istanbul University, between January 2000-Decernber 2002; to compare the resistance of these GNRs to selected antibiotics; and to determine the prevalence of extended-spectrum beta-lactamases (ESBLs). A total of 367 isolates were obtained from 171 patients. Susceptibility testing and detection of ESBLs were performed using the E-test method. Ceftazidime-clavulanate was used for the detection of ESBLs. The majority of microorganisms were isolated from the respiratory tract (45.5%) and blood (36.7%). Acinetobacter baumannii was the most frequently isolated GNR (24.5%), followed by Pseudomonas aeruginosa (22%). ESBL positivity was found to be 21.1%. High rates of the ESBLs of Escherichia coli and Klebsiella pneumoniae were observed, i.e., 27.7 and 57.5%, respectively. High rates of resistance to all antibiotics studied were observed. The most active agent against the majority of the isolates was imipenem (79.2%), followed by levofloxacin (77%) and ciprofloxacin (71%).