OBJECTIVE: Recognizing the effect of prescription drug coverage on the patient's ability to obtain prescription drugs is crucial and may play an important role in the health care decision making process due to the associated cost and the potential for misutilization. It is the objective of this study to provide specific information on the influence of prescription drug coverage on antibiotic utilization in acute respiratory tract infections (RTIs). METHODS: A retrospective study of (N=3181) prescription events associated with acute upper and lower RTIs have been identified from the Household Component (HC) of the 1996 Medical Expenditure Panel Survey (MEPS). Cases selected included acute nasopharyngitis (common cold), acute sinusitis, acute pharyngitis, acute tonsillitis, acute laryngitis and tracheitis, acute upper RTIs of multiple or unspecified sites, and acute bronchitis and bronchiolitis. Antibiotic use and associated costs were determined by selecting oral antibiotics and the sum of payment associated with each prescription. Logistic regression was used to evaluate prescription drug coverage effect on prescribing an antibiotic and on the type of antibiotic prescribed. RESULTS: Antibiotics accounted for 45.93% of the prescription events for acute RTIs, of which 25.46% were for high cost antibiotics. When compared to patients with prescription drug coverage, patients with no drug coverage were less likely to be prescribed an antibiotic (OR: 0.499; 95% CI: 0.407 - 0.612), and they were also less likely to receive a high cost antibiotic (OR: 0.096; 95% CI: 0.059 - 0.157). CONCLUSION: The results of the study indicate that, in acute RTIs, the likelihood of being prescribed an antibiotic, that may be unnecessary, is greater when the patient has prescription drug coverage. Providers of such coverage should closely monitor prescribing patterns for acute RTIs to avoid unnecessary cost and consequently, resistance from such antibiotics.