Introduction - A study covering the 2012–2017 seasons showed that seasonal influenza surveillance in France did not allow for a comprehensive assessment of the impact of influenza outbreaks on the hospital system. It was recommended to conduct a systematic annual analysis of hospital stays using the Medical Information Systems Program (PMSI) to provide a retrospective, age-stratified analysis of the epidemic’s impact on the hospital system. Materials and Methods - All hospital stays occurring in metropolitan France between July 1, 2017, and June 30, 2018, with a diagnosis of influenza (ICD-10 codes J09 to J11) as the primary, related, or associated diagnosis were extracted from the PMSI. Hospitalization rates by patient age group, the proportion of patients admitted to intensive care units, case fatality rates, and length of stay were described and compared with the four previous influenza seasons. Thresholds for epidemic intensity were determined for each age group and each season. Results - During the 2017–2018 influenza season, 44,750 hospital stays with a diagnosis of influenza were identified. Two epidemic peaks occurred, the first affecting young people in particular and the second those aged 40–79, resulting in a hospitalization rate higher than the average of the four previous seasons. The proportion of hospitalizations requiring intensive care (10%), the case fatality rate (5.8%), and the average length of stay (8.6 days) were similar to those of previous seasons. Conclusion - While real-time surveillance is essential for tracking the progression of the epidemic and its severity, analysis using the PMSI is necessary to provide a more comprehensive assessment of the impact on the hospital care system.