During the 2009/10 influenza A/H1N1v pandemic in Switzerland, we followed the disease course of of all 15 patients with A/H1N1v-associated pneumonia whom we identified at our tertiary care hospital. Eight of the patients had previously known risk factors for A/H1N1v disease compliction, according to WHO criteria. All patients showed signs and/or symptoms of complicated influenza. 14 patients had to be hospitalised with a median hospital stay of 8–9 days; 6 were admitted to intensive care, of whom 3 required intubation. According to WHO recommendations, oseltamivir should be started as early as possible, both in patients with risk factors for severe disease and in any patient presenting with symptoms of progressive disease. If treated early according to these guidelines, half of our patients might not have developed pneumonia at all. In the remaining patients without preexisting risk factors, the clinical course of pneumonia might have been milder. It is questionable whether the delayed oseltamivir treatment still influenced the clinical outcome, but no patient died; the two patients who were discharged with new home oxygen therapy apparatus had presented massive preexisting morbidities.