Previous investigation revealed that plan members diagnosed with conditions that usually have a viral etiology receive antibiotics at high rates. Multiple reasons exist for this inappropriate drug use. One possible reason may be that providers, patients, or both believe that using an antibiotic will prevent the onset a more serious condition and thereby prevent a return visit. Identification of the causes of antibiotic use will help design interventions to control the development of antibiotic-resistant microorganisms. OBJECTIVE: Determine the impact of antibiotic use on return visits for acute respiratory tract infections. METHODS: This study uses large database analysis (insurance claims data). Inclusion criteria: age less than 65 and continuous enrollment in a non-HMO benefit plan with medical, hospital, and pharmaceutical coverage. Cases were identified as an outpatient service for a common cold, upper respiratory tract infection, or acute bronchitis. Antibiotic use was defined as a prescription filled within seven days of the respiratory tract infection. Patients were followed for an additional 30 days to determine whether they had a subsequent service for a respiratory tract infection or related condition. RESULTS: There were 173,469 patients who met study criteria, overall 101,446 received antibiotics (58.48%). For those who received an antibiotic, 14,600 (14.39%) returned for a respiratory tract infection within 30 days of their initial diagnosis. Of those not receiving an antibiotic at their first visit (72,023), 12.27% returned for a subsequent respiratory tract infection within 30 days of their initial diagnosis. Although the difference between the groups is statistically significant (p<0.0001), the magnitude is not clinically significant. CONCLUSION: The use of antibiotics for acute respiratory tract infections does not affect the rate of return for subsequent visits within 30 days. Communicating this information to providers and patients could help reduce the inappropriate use of antibiotics.