OBJECTIVES: To address the paucity of HIV-related lymphoma (HRL)-specific prognostic scores for the Japanese population by analyzing domestic cases of HRL and constructing a predictive model. DESIGN: A single-center retrospective study coupled with a review of case reports of HRL. METHODS: We reviewed all patients with HRL treated at our hospital between 2007 and 2023 and conducted a comprehensive search for case reports of HRL from Japan using public databases. A multivariate analysis for overall survival (OS) was performed using clinical parameters, leading to the formulation of the HIV-Japanese Prognostic Index (HIV-JPI). RESULTS: A total of 19 patients with HRL were identified in our institution, whereas the literature review yielded 44 cases. In the HIV-JPI, a weighted score of 1 was assigned to the following factors: age at least 45 years, HIV-RNA at least 8.0×10 4  copies/ml, Epstein-Barr virus-encoded small RNA positivity, and Ann Arbor classification stage IV. The overall score ranged from 0 to 4. We defined the low-risk group as scores ranging from 0 to 2 and the high-risk group as scores ranging from 3 to 4. The 3-year OS probability of the high-risk group [30.8%; 95% confidence interval (CI): 9.5-55.4%) was significantly poorer than that of the low-risk group (76.8%; 95% CI: 52.8-89.7%; P  < 0.01). CONCLUSION: This retrospective analysis established pivotal prognostic factors for HRL in Japanese patients. The HIV-JPI, derived exclusively from Japanese patients, highlights the potential for stratified treatments and emphasizes the need for broader studies to further refine this clinical prediction model.