Background - Enhanced passive surveillance for influenza A(H1N1) cases was implemented during the 2009–2010 season among people living with HIV (PLHIV) in the ANRS CO3 Aquitaine Cohort. Materials and Methods - Each week, the 20 participating hospital physicians were required to spontaneously report clinically suspected cases and RT-PCR-confirmed diagnoses of influenza A(H1N1). To evaluate the performance of this system, the results were subsequently cross-checked against two other sources of information: the virology laboratory at Bordeaux University Hospital and the Gecsa/Corevih information system. Results - Between November 2009 and April 2010, 13 suspected cases and 3 biologically confirmed cases of influenza A(H1N1) were reported among 3,336 PLHIV under follow-up. These data are consistent with the 6 cases biologically confirmed by the virology laboratory and the 6 diagnoses routinely recorded in the Aquitaine Cohort database during this period. Discussion-Conclusion - This hospital-based surveillance system for patients living with HIV has demonstrated its ability to rapidly incorporate a new cause of morbidity. It could be reinstated in the event of a new epidemic threat within this population. (R.A)