We analyzed 67 adenovirus isolates from 48 patients with AIDS. The isolates included 5 of subgenus A (all Ad31), 23 of subgenus B, 4 of subgenus C (all Ad5), and 35 of subgenus D. The subgenus A and C strains were from liver, lung, blood, urine, and stool and were unremarkable in their antigenic characteristics. The subgenus B strains were mostly from urine and were serotyped by neutralization (SN) and hemagglutination-inhibition (HAI) tests as Ad11 (12 isolates), Ad16 (1), Ad35 (3), and Ad21/H21 + 35 (1) plus new intermediate strains 34/H11 (3), 35/H11 (1), and 11 + 35/H11 (2). The subgenus D serotypes from 24 patients were mostly from stool specimens and consisted of 8 isolates of known serotypes, 16 of antigenically intermediate strains, and 11 of five new adenovirus types with distinct antigenic and restriction enzyme characteristics. The new serotypes were described as candidate types 43-47 in accordance with currently accepted taxonomic criteria. Ad45, 46, and 47 showed a major relation by HAI with Ad29, 24, and 20, respectively. Four intermediate types were related to the new serotypes. The plethora of serotypes from patients with AIDS suggests that no epidemiological significance can be attached to any one serotype.