The main goal of this study was to compare the utilization of antibiotics in different wards of a university hospital. Consumption of antibacterial drugs rose dramatically during years 2000-2005 in Iran. Data collected during first half of year 2000 and 2005 in Emam University Hospital in city of Sari in Iran, showed use of antibiotics jumped from 95.4 DBDs (Defined Daily Doses per patient's bed-days) to 124 DBDs. Distribution of different class of anti-microbial showed highest increase in use of vancomycin with 28.4 folds and clindamycin with 4.8 fold. Use of cotrimoxazole, aminoglycosides and tetracyclines remained fairly unchanged during this period. However, during the same period, consumption of penicillin G, aminopenicillins and cloxacillin dropped 10.3, 3.8 and 3 fold, respectively. Among university hospital departments, oncology ward followed by ICU and general surgery consumed the most antibacterial agents in year 2000. In year 2005, ICU ward followed by gynecology, oncology and orthopedic were among the University Hospital Departments with highest consumption of antibiotics. The most highly used antibiotics in year 2000 were cefazolin followed by ampicillin, ceftizoxime and gentamicin. In year 2005, cefazolin, ceftriaoxone, gentamicin and ciprofloxacin were the most prescribed antibiotics. Injectable antibiotics accounted for 51.8 and 79.4% of total DBDs in first half of years 2000 and 2005, respectively. The bulk of prescription (90% of total DBDs) was made up of 13 out of 32 total antibiotic types in 2000 and 11 out of 29 total antibiotics types in 2005. Comparing with similar hospitals in other countries, data presented show a dramatic increase in antibiotics prescribed by physician in Emam University Hospital.