In the Southern Hemisphere, Réunion serves as a sentinel for infections that primarily occur during the Southern Hemisphere winter and are likely to spread to the Northern Hemisphere a few months later, such as the A(H1N1)v2009 infection. We report the characteristics of patients admitted in 2009 and 2010 to our intensive care unit primarily for acute respiratory distress following A(H1N1)v2009 infection. Demographic, clinical, and laboratory data, as well as treatments and outcomes for patients admitted for A(H1N1)v2009 viral infection confirmed exclusively by RT-PCR, were collected prospectively. During 2009 and 2010, 25 patients met the defined criteria for A(H1N1)v2009 infection. The median age was 40.4 (±17.4) years. Most of them (22/25) had comorbidities: chronic conditions, overweight or obesity, pregnancy, or Down syndrome. The main reasons for admission to the intensive care unit were viral pneumonia with acute respiratory distress syndrome. Mechanical ventilation was required in 22 of the 25 patients, involving sophisticated methods available only at a few centers nationwide, such as extracorporeal membrane oxygenation (ECMO) or high-frequency ventilation (HFO). Over the two-year period, 12 deaths (48%) occurred, primarily due to multiple organ failure. During the southern hemispheric winters and autumns of 2009 and 2010, and over a period of several weeks, the A(H1N1) v2009 infection led to a significant surge in activity in the intensive care units on Réunion. The failure of the vaccination campaign, particularly among at-risk individuals, resulted in the emergence of new severe cases in 2010, particularly among at-risk individuals. The collection of these data can aid in planning and anticipating the management of future influenza epidemics. (R.A.)