Background - In France, the risk of HIV transmission through blood transfusion has been substantially reduced by the introduction of pooled viral genomic screening (MP-DGV) in 2001, followed by individual screening (ID-DGV) in 2010. We report here the first case of transfusion of labile blood products infected with HIV, collected during the very early phase of infection, during which ID-DGV was negative. Methods - The biological qualification of blood donations for HIV includes screening for anti-HIV-1/2 antibodies and viral load testing (ProcleixUltrio, Grifols, 95% lower detection limit (LDD95) = 23 copies/mL). Upon a donor’s seroconversion, one of the archived samples from the previous donation is retested using the Cobas Taqman HIV-1 (CTM, Roche, LDD95 = 17 copies/mL) assay. Results - In August 2017, a 57-year-old regular donor tested positive for HIV (with a plasma viral load (pVL) of 11,599 copies/mL). The previous donation, which was negative by ID-DGV, tested positive by CTM, although the pVL was not quantifiable. Sequencing of the strain showed no mismatches with the Ultrio reagent’s primers/probe. HIV transmission could be ruled out in the platelet recipient who underwent a pathogen-reduction procedure. However, HIV transmission could not be documented in the red blood cell recipient, who died prematurely. Conclusion - This case demonstrates that the risk of encountering labile blood products infected with HIV that test negative by ID-DGV, when a donation is made during a biologically silent phase of infection, is real, albeit exceptional. HIV transmission could not be formally ruled out in one of the two recipients. This case also highlights the importance of systematically archiving plasma samples from donations, as well as the selection and education of blood donors.