From 1976 to 1990 for 15 consecutive epidemic years, virological examinations were carried out on 2,757 hospitalized infants and children infected with pneumonia. Ninety-nine strains of types 3 and 7 adenovirus (Ad3,Ad7) isolated from 50s to 90s were analyzed with 12 DNA restriction endonucleases. Results showed the epidemiologic characteristics of adenovirus (Adv) pneumonia in Beijing. Epidemic occurred yearly, but there was no severe outbreak of Adv pneumonia as in 1958. Ad3 and Ad7 were the main etiologic agents of Adv pneumonia. Ad7 was dominant in 1976-1980; while Ad3 was more prevalent in 1981-1990. DNA restriction endonuclease analysis revealed six genome types of Ad7 and three genotypes of Ad3. 7a1, 7a4, 7b and 7g occurred in 1958, 1965, but disappeared between 1980-1990; 3a2 was first detected in 1962. From 1980 to 1990, 7d and 3a2 were the dominant genome types. Among the Ad7 strains only one strain of 7d1 was identified; all others were 7d. 3a4 and 3a6 first appeared in 1984 and 1986, respectively. The changes of epidemic patterns seemed correlated with the variations of genome types.