BACKGROUND The spread of antibiotic-resistant bacteria is associated with antibiotic use. Children receive a significant proportion of the antibiotics prescribed each year and represent an important target group for efforts aimed at reducing unnecessary antibiotic use. OBJECTIVE To evaluate antibiotic-prescribing practices for children younger than 18 years who had received a diagnosis of cold, upper respiratory tract infection (URI), or bronchitis in the United States. METHODS Representative national survey of practicing physicians participating in the National Ambulatory Medical Care Survey conducted in 1992 with a response rate of 73%. METHODS Office-based physician practices. METHODS Physicians completing patient record forms for patients younger than 18 years. METHODS Principal diagnoses and antibiotic prescriptions. RESULTS A total of 531 pediatric office visits were recorded that included a principal diagnosis of cold, URI, or bronchitis. Antibiotics were prescribed to 44% of patients with common colds, 46% with URIs, and 75% with bronchitis. Extrapolating to the United States, 6.5 million prescriptions (12% of all prescriptions for children) were written for children diagnosed as having a URI or nasopharyngitis (common cold), and 4.7 million (9% of all prescriptions for children) were written for children diagnosed as having bronchitis. After controlling for confounding factors, antibiotics were prescribed more often for children aged 5 to 11 years than for younger children (odds ratio [OR], 1.94; 95% confidence interval [CI], 1.13-3.33) and rates were lower for pediatricians than for nonpediatricians (OR, 0.57; 95% CI, 0.35-0.92). Children aged 0 to 4 years received 53% of all antibiotic prescriptions, and otitis media was the most frequent diagnosis for which antibiotics were prescribed (30% of all prescriptions). CONCLUSIONS Antibiotic prescribing for children diagnosed as having colds, URIs, and bronchitis, conditions that typically do not benefit from antibiotics, represents a substantial proportion of total antibiotic prescriptions to children in the United States each year.