Periodontal status was evaluated in two cohorts participating in a study of the natural history of human immunodeficiency virus (HIV) infection. One cohort consisted of 77 seropositive and 44 seronegative homosexual men, and the other cohort was comprised of 44 seropositive and 39 seronegative parenteral drug users (PDU). No differences were observed between seropositive and seronegative individuals within a cohort in terms of clinical periodontal parameters (percent of sites with > or = 4 mm probing depth, percent of sites exhibiting bleeding on probing, mean oral hygiene index). The PDU displayed more existing periodontal disease than the homosexual men. Periodontal disease in the seropositive individuals in both cohorts was not strictly related to the number of CD4+ lymphocytes. Linear gingival erythema (LGE), defined as an erythematous band of at least 2 mm extending between adjacent papilla, was observed in all 4 groups. Seropositive homosexual men displayed more LGE than seronegative homosexual men (16.6% vs. 11.4%) and seronegative PDU displayed more LGE than seropositive PDU (38.5% vs. 29.5%), but neither difference was significant. LGE tended to be related to reduced numbers of CD4+ lymphocytes, but this relationship did not reach statistical significance. A statistically-significant relationship was found between the presence of intraoral candidiasis and LGE in seropositive homosexual men: 42.9% of these subjects with candidiasis had LGE, while only 12.7% of the subjects without candidiasis had LGE (P < .05). For the seropositive PDU, 35.3% of the individuals with candidiasis had LGE and 25.9% of the subjects without candidiasis displayed LGE, but the difference was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)