This case report describes and discuss the significance of necrotizing ulcerative periodontitis. A wide range of oral lesions has been documented in individuals infected with the potential life-threatening human immunodeficiency virus (HIV). HIV-infected patients are at an increased risk of a unique form of periodontal disease called ‘necrotizing ulcerative periodontitis’. These lesions are the most severe form of periodontitis identified but of rare occurrence among HIV patients, with a prevalence of less than 5%. Disease progress is managed by thorough local debridement under antibiotic coverage. Here, we report a case of a 44-year-old female who reported with an extensive area of ulcerations, and necrosis of marginal gingiva, interdental papilla, and attached gingiva. Blood investigations revealed an absolute CD4+ cells count of 75 cells/mm3 and HIV-positive status. Necrotizing ulcerative periodontitis is as an indicator of underlying systemic immunosuppression. Further, the occurrence of ulcerative periodontitis led to the diagnosis of HIV in the present case.