The epidemiologic and etiologic features of cases of pneumonia among 1,740 children admitted to a teaching hospital in Hong Kong over a 3-year period were studied. Of the patients, 23% were Haemophilus influenzae was the bacterial agent most frequently isolated from nasopharyngeal aspirates or sputum, followed by Streptococcus pneumoniae and Staphylococcus aureus. Of the H. influenzae isolates, 38% were resistant to ampicillin. A viral etiology was proven in 9.1% of cases, and evidence of mycoplasmal infection was found in 3.8% of cases. Respiratory syncytial virus was the most frequently identified viral agent, followed by adenovirus and influenza A virus.