Fifty-six patients were referred in 1983 for assessment in connection with AIDS and related disorders. Clinical and immunological classification of patients was carried out according to the NHMRC criteria. The presence of antibodies to an AIDS-associated retrovirus (ARV) was determined in some patients. Of the 32 patients who could be categorized, three patients had AIDS, and all three had serum antibodies to ARV. Fifteen patients had lymphadenopathy syndrome with impaired T-cell immunity. Ten of 12 patients tested had antibodies to ARV. Symptomatic illnesses resembling lymphadenopathy syndrome, but without immune defects, occurred in nine patients. By contrast, five patients who had no symptoms had impaired immunity, and in seven patients no clinical and immunological abnormalities were found. The classification proposed by the NHMRC was found to be useful in delineating several major clinical and immunological patterns of response to infection with the AIDS-associated retrovirus.