In 2002, antimicrobial drugs were the most frequently prescribed drugs in Turkey. On February 15, 2003, the Turkish Government implemented a new Budget Application Instruction (BAI) to promote rational antibiotic usage in order to decrease the costs. This BAI restricted the reimbursement of certain antibiotics without prescription or approval by the infectious diseases specialists (IDS). The purpose of this study is to evaluate the effect of BAI on antibiotic consumption for the 3 years before and 2 years after its implementation, according to IMS Health Office findings. Based on the data of the IMS Health Turkey Office, the amount of some broad-spectrum antibiotics (piperacillin/tazobactam, imipenem, meropenem, cefoperazone/sulbactam, ceftazidime, cefepime, teicoplanin, vancomycin, and amphotericin B) that were prescribed by IDS between 2000 and 2002 and between 2003 and 2004 are determined. The Anatomical Therapeutic Chemical classification and the defined daily dose (DDD)/1,000 methodology are used to calculate antibiotic consumption. Total antibiotic consumption before BAI, in 2000, 2001 and 2002 was 0.091, 0.107 and 0.119 DDD/1,000 inhabitant-days, respectively, and after BAI, in 2003 and 2004, 0.137 and 0.135 DDD/1,000 inhabitant-days, respectively. Average utilization of antibiotics before the implementation of BAI was 0.105 DDD and increased to 0.136 DDD after BAI. Antibiotic consumption has increased 1.3-fold after the implementation of BAI. However, the effect of restricted antibiotic utilization was revealed especially in the second year after BAI. The consumption of antimicrobials decreased to 0.135 in 2004 while it was 0.137 in 2003.