Background and Purpose: Excess use of antimicrobials by ambulatory patients is a determinant of antimicrobial resistance. This study investigated the types of illnesses for which antimicrobials were prescribed and the amounts prescribed with special emphasis on respiratory infections for the year in which the Bureau of National Health Insurance (BNHI) enforced a policy to restrict antimicrobials for upper respiratory infections. The number of ambulatory patients seen and the types of ambulatory facilities in Taiwan were also described. Methods: Raw data were obtained from the BNHI database on every 500th visit in 2001. Medical diagnoses were categorized according to the ICD-9-CM system. Antimicrobial consumption was expressed in defined daily doses per 1000 population per day (DDD/1000/day). Results: Among the population of 22.3 million in Taiwan, there were 285.8 million ambulatory patient visits (12.8 per person), including 108.9 million visits (4.9 per person) for respiratory infections, of which 62.7 million (2.8 per person) were for upper respiratory infections (URI). Antimicrobial consumption was 19.83 DDD/1000/day [standard error (SE), 0.00055], of which 9.97 DDD/1000/day (SE, 0.00047) were for respiratory infections and 4.03 DDD/1000/day (0.00055) were for URI. 23.6% of visits for URI entailed a prescription for antimicrobials. About two-thirds (66.5%) of ambulatory patients were seen in clinics, mostly private ones, and 67.6% of all antimicrobials were received there. Aminopenicillins and cephalosporins constituted 35.2% and 19.5%, respectively, of antimicrobials prescribed. Conclusions: Despite the new BNHI rule restricting antimicrobial usage for URI, Taiwan still has an excessive number of ambulatory patient visits, especially for respiratory infections and URI. The majority of antimicrobials used were for URI. They were mostly prescribed in private clinics rather than hospital outpatient departments.