In the Netherlands, all deaths associated with laboratory-confirmed influenza A(H1N1) 2009 virus infection had to be notified since 30 April 2009. This mandatory notification remained in place during the influenza season 2010-2011, which in Europe has been characterized predominantly by the influenza A(H1N1) 2009 virus, and to a lesser extent influenza virus type B [12, 13] . The national notification system provided detailed information of the clinical characteristics of all deaths associated with a laboratory-confirmed influenza A (H1N1) 2009 virus infection in the Netherlands. We performed a retrospective analysis of all fatalities, comparing the 2009-2010 pandemic season with the 2010-2011 influenza season, aiming to assess whether and to what extent pandemic mortality patterns concerning age distribution and underlying conditions were reverting to seasonal patterns.