AIM: To report the frequency of oral lesions in HIV-positive patients on Highly Active Antiretroviral Therapy (HAART), comparing with a non-HIV infected control group, and to correlate the presence of lesions with demographic and clinical features of HIV-seropositive patients. METHODS: A quantitative case-control study was conducted by a dental professional, using a questionnaire, analysis of medical records of patients and clinical examinations. RESULTS: According to the results, oral lesions were found in 23% of HIV-positive patients versus 5% in controls. Candidiasis (29%) and periodontal changes (25%) were the most frequent oral lesions found in these patients. Gender and viral load values were statistically significant when HIV-positive patients with and without oral lesions were compared. CONCLUSIONS: The results showed a change in lesion pattern of HIV patients on HAART, highlighting a high frequency of these new lesions and reinforcing the need for periodic dental evaluation of HIV-positive patients.