Pré-publication, Document de travail: Background In 2011, migrants accounted for 47% of newly diagnosed cases of HIV infection in France, including 70% from Sub-Saharan Africa. These populations meet with speci_c obstacles leading to late diagnosis and access to medical and social care. Reducing these delays has a proven benefit to patients' health and contributes to a better control of the epidemic by preventing secondary infections. Methods The objective of this study is to assess the cost-effectiveness impact of an early access to care (ATC) for migrant people living with HIV (PLHIV) in France. The model compares early" vs. late" ATC for migrant PLHIV in France, defined by an entry into care with a CD4 cell count of 350 and 100/mm3 respectively, and integrate the positive externality of treatment on prevention. To evaluate the cost-effectiveness of early" ATC, incidence and hidden prevalence among migrants in France were estimated. Findings Early ATC strategy proved cost-saving, or cost-effective in the worst case scenario. In the most favorable scenario, early ATC generated an average net saving of €198,000 per patient, and prevented 0.542 secondary infection. In the worst case scenario, early ATC strategy generated an average cost of €28,000, a cost-effectiveness ratio of €133,000 per averted infection and prevented 0.211 secondary infection. Interpretation In addition to individual health benefit, improving early ATC for migrant PLHIV proves an efficient strategy in terms of public health and economics. These results stress out the benefit of ensuring ATC for all individuals living with HIV in France.