Between February 1987 and February 1990, we studied 737 antibody anti HIV-1 positive (AbHIV+) subjects referred to the Infectious Diseases Institute of the University of Turin (Italy) in order to evaluate types, prevalences, relations with clinical stages, distributions in risk-groups and prognostic significances of HIV-1 related oral lesions. The study evidenced the high prevalence of oral lesions, especially mycoses, in the investigated population: 40.3% of the patients showed, in fact, HIV-1 related oral lesions. The 37 months follow-up of 55 AbHIV+ with oral hairy leukoplakia (HL) and 101 patients with oral candidiasis (OC), demonstrated that the probability of developing AIDS in patient with HL was 0.381 at 15, 0.635 at 25 and 0.824 at 37 months. In the patients with OC the probability was 0.294 at 15 months, 0.524 at 25 and 0.781 at 37 months.