Objective: To analyze the trend in antiviral prescriptions for patients with influenza from 1999-2005. Methods: This is a cross-sectional database analysis using data from the NAMCS (National ambulatory medical care survey) and NHAMCS (National hospital ambulatory medical care survey) for the years 1999-2005. Records were extracted for office and hospital based physician-patient encounters having a diagnosis of influenza (ICD-9-CM codes 487.0, 487.1, 487.8). The rate of neuraminidase inhibitors (NI) and adamantanes prescribed per 1,000 patients with influenza was determined. The association between the type of antiviral drug and the physician specialty, region, patient sex, and patient age was evaluated by adjusted odd ratios. Data were analyzed with Proc logistic regression with adjusted odds ratios by years using SAS® 9.1.3. Results: The prescribing rates of NI per 1,000 cases ranged from 11 to 175 per year for office-based encounters and 0 to 311 for hospital-based encounters. Adamantane prescribing rates ranged from 23 to 194 for office-based encounters and 5 to 172 for hospital-based encounters. Odds ratios of adamantanes rather than NIs were 26.6(P<0.0001) for 1999, 0.034 for 2000, 0.011 for 2001, 0.058 for 2002, 0.002 for 2003, 0.178 for 2004 (p<0.001). Whites (OR: 9.4, p<0.001), females (OR: 1.8. p<0.001), patients under 55 (OR: 0.4-0.53, p<0.001), and patients from the West (OR: 2.7-33.9, p<0.001) were most likely to get adamantanes. Conclusion: NI usage slowly increased from 1999-2005. Office-based encounters had a greater rate of prescriptions for adamantanes than hospital-based encounters. In months other than flu season patients were less likely (OR: 0.06, p<0.001) to get adamantanes. General practitioners were less likely (OR: 0.5, p<0.001) to prescribe adamantanes than other specialties. Patient age, race, sex, physician specialty, and geographic region were significantly related to prescribing patterns. In 2005, patients were more likely to get adamantanes in spite of high incidence of adamantane resistant viruses.