Cytomegalovirus isolates can be grouped into 4 gB and 2 gH genotypes. gB genotypes were studied in patients infected with human immunodeficiency virus (HIV) and in allograft transplantation recipients. In allograft recipients, the distribution of gB 1, -2, -3, and -4 in leukocytes and urine, respectively, was 36%, 21%, 43%, and 0% and 39%, 30%, 17%, and 13%. However, in leukocytes of HIV-infected patients with <100/microL CD4 cells, gB1 was found significantly less often than in allograft recipients (11% vs. 36%) but gB2 was more frequent (56% vs. 21%; P < .05). The decreased incidence of gBl and increased incidence of gB2 compared with allograft recipients was also seen in urine of HIV-infected patients and reflected the distribution seen in leukocytes. gB4 was found significantly more often (P < .05) in semen than in leukocytes of HIV-infected patients with < 100/microL CD4 cells. gB1-4 genotypes were similar in patients with < 100/microL CD4 cells with or without retinitis.