A multitude of oral lesions have been described in individuals infected with the human immunodeficiency virus (HIV). Few studies have attempted to correlate specific oral findings with immune status and HIV disease progression in the population reflecting the demographic profile of this epidemic. A prospective study was conducted among 700 ambulatory HIV-infected individuals seeking dental care between July 1, 1988 and June 30, 1992. Patients entered the study when they first applied for care and were followed at regular intervals unless death occurred before the conclusion of the study. The prevalence rate of necrotizing ulcerative periodontitis (NUP) was calculated for the entire population and specific to race, gender, and HIV transmission category. Survival analysis was used to estimate the cumulative probability of death within 24 months of a NUP diagnosis. The association between NUP diagnosis and CD4+ cell count below 200 cells/mm3 was also investigated, and it was found that HIV-infected individuals presenting with a diagnosis of NUP were 20.8 times as likely to have a CD4+ cell count below 200 cells/mm3 compared to HIV-infected individuals presenting without NUP. The prevalence of NUP was 6.3%. The lesion was significantly more common among men having sex with men (MSM), 8.4%, compared with non-MSM males, 1.8%. No racial difference was noted. The mean CD4+ cell count for patients with NUP was 51.8 cells/mm3 (SD +/- 71.2) while the median CD4+ cell count was 32.0 cells/mm3. The predictive value of a CD4+ cell count below 200 cells/mm3 in patients with this lesion was 95.1%. A cumulative probability of death within 24 months of a NUP diagnosis was 72.9%.(ABSTRACT TRUNCATED AT 250 WORDS)