OBJECTIVES: To determine the impact of hospital caseload size on HIV virological success when taking into account individual patient characteristics. METHODS: Data from the ANRS-VESPA2 survey representative of people living with HIV in France was used. Analyses were carried out on the 2612 (86.4% out of 3022) individuals receiving antiretroviral (ARV) treatment for at least one year. Outcomes correspond to two definitions of virological success (VS1 and VS2 respectively) and were analyzed under a multi-level modeling framework with a special focus on the effect of the caseload size on VS. RESULTS: Structures with caseloads <1700 patients were more likely to have increased the proportion of patients achieving virological success (59% and 81% for VS1 and VS2, respectively) than structures whose caseloads numbered ≥1700 patients. Our results highlight that patients in the 11 largest care units in the sample were exposed to a context where their VS was potentially compromised by care unit characteristics, independently of both their individual characteristics and their own HIV treatment adherence behavior. CONCLUSIONS: Our results suggest that - at least in the case of HIV care - in France large care units are not necessarily better. This result serves as an evidence-based warning to public authorities to ensure that health outcomes are guaranteed in an era when the French hospital sector is being substantially restructured.