We describe the clinical characteristics of 209 children younger than 15 years of age with positive pharyngeal cultures for adenovirus. The mean age of the children was 37 +/- 33 months, and the mean peak temperature was 39.2 +/- 0.76 degrees C. On physical examination, tonsillitis was found for 88% of children; 52% of them had exudative tonsillitis. Forty-eight percent of the patients who had a white blood cell count performed had >15,000 leukocytes per mm, and 25% had >20,000 leukocytes per mm. C-reactive protein concentrations were >7 mg/dL for 22.5% of the patients. Adenovirus pharyngeal infections in young children mimic severe bacterial infections.