Purpose: To undertake an audit of the antimicrobial (AM) sensitivity pattern of bacterial isolates in the intensive care units (ICU) of a tertiary hospital of Bhavnagar, India. Methods: Retrospective analysis of the indoor case papers of ICUs from January 2010 to 31st March 2011 was carried out at Department of Pharmacology, Govt. Medical College and Sir Takhtsinhji General Hospital, Bhavnagar, India. Information collected include demographic data of the patient, admission unit, duration of hospital stay, diagnosis, type of infection, empirical treatment, indication of the use of the antimicrobials (AMs). Others include collected specimen, causative agent, sensitivity pattern, and treatment changes based on the sensitivity pattern in a case record form. AM sensitivity testing was performed by the modified Kirby Baur method as recommended by clinical and laboratory standard institute (CLSI). Internal and external quality control were maintained for culture and sensitivity method. Results: The most commonly isolated organisms were Klebsiella pneumoniae (28.6 %) and Pseudomonas aeruginosa (16.3 %). Lower respiratory tract infection (LRTI) was the most common infection. Imipenem, meropenem and levofloxacin were the most effective antimicrobials for Gramnegative isolates (GNIs) while vancomycin ciprofloxacin, and gentamicin were the most efficacious antimicrobials for Gram-positive isolates (GPIs). Widespread resistance to third generation cephalosporins and cloxacillin was noted for GNIs and GPIs, respectively. Meropenem (100 %) > levofloxacin (100 %) > sparfloxacin (94.4 %) > gentamicin (83.3 %) was the rank order of antimicrobial activity against LRTI. Conclusion: GNIs were the predominant cause of infection in ICUs. Third generation cephalosporinsresistant GNIs were the predominant resistant organisms. The study showed that fluoroquinolones and aminoglycosides could be used as first line AMs for the effective management of LRTI in a hospital setting.