Background: The aim of this study is to evaluate the periodontal status and the presence of opportunistic oral lesions in human immunodeficiency virus–positive (HIV+) patients under highly active antiretroviral therapy (HAART) and their association with cluster of differentiation (CD)4+ and CD4+ nadir T-cell counts and viral load levels. Methods: Clinical periodontal parameters and the presence of opportunistic oral lesions along with records of CD4+ counts and viral load levels were evaluated in 29 individuals (16 females; mean age: 42.7 years) with previous serologic diagnosis of HIV, from the acquired immunodeficiency syndrome program of the Health Center of Duque de Caxias, Rio de Janeiro, Brazil. Results: All individuals presented gingivitis or periodontitis. A higher non-significant prevalence of periodontitis was found in smokers (93.8%) compared with non-smokers (76.9%). A significant weak positive correlation was observed between CD4+ counts and missing teeth (r = 0.380, P <0.05), CD4+nadir and periodontal diagnosis (r = 0.418, P <0.005), and CD4+ nadir and moderate probing depth (PD) (r = 0.424, P <0.05). When only non-smokers were analyzed, a significant moderate positive association was found between viral load and moderate clinical attachment level (CAL) (r = 0.638, P <0.05), CD4+ nadir and diagnosis (r = 0.586, P <0.05), and CD4+ nadir and moderate CAL (r = 0.680, P <0.05). Analysis considering only smokers found no correlations between serologic parameters and demographic or clinical parameters. Conclusions: The current investigation demonstrates that HIV+ individuals under HAART presents a high prevalence of mild to moderate periodontal disease. Viral load levels, CD4+ nadir, and CD4+ counts may present a weak to moderate correlation to the number of missing teeth, periodontal diagnosis, moderate PD, and moderate CAL, which may also reflect some effect of these systemic conditions on the periodontal status.