The explosive outbreak of pandemic influenza A (H1N1) in Argentina lasted about six weeks, from mid May to late June, with widespread transmission across the country. Influenza virus represented 82.13% of the cases reporting respiratory virus. Consultations for influenza-like illness in general practices and emergency departments peaked at 309 consultations for every 10,000 inhabitants. Children and young adults were the age groups most affected. From 7 May to 31 October, 2009, 10,248 confirmed cases, 12,471 hospitalizations for severe respiratory disease, and 600 deaths were reported to the Ministry of Health. The most affected group was children under 5 years of age (hospitalization rate 72.99/100,000), followed by the 45–54 year age group. In this latter group, the most frequent preexisting conditions were cardiovascular, respiratory, and metabolic diseases. As in other countries, obesity and pregnancy were risk factors for increased morbidity. The experience of this first pandemic wave has taught us that coordinated work, community education, early treatment with antiviral drugs, and vaccine administration during the next season for high-risk groups are likely to be fundamental tools against the next pandemic wave.