Pneumocystis jirovecii pneumonia is the main cause of severe respiratory failure in patients with advanced HIV disease who do not receive P. jirovecii prophylaxis. Other aetiological agents may contribute to the respiratory failure in these patients, which is highlighted by the case described below: A patient with advanced HIV disease was treated for a dual-infection with pandemic influenza A (H1N1) and P. jirovecii. Initially, his condition improved, but deteriorated after the emergence of oseltamivir-resistant influenza virus. This is the first documented case of emergence of drug-resistant influenza virus in a patient infected with HIV with a pandemic influenza A (H1N1) and P. jirovecii double infection. J. Med. Virol. 85: 941943, 2013. (c) 2013 Wiley Periodicals, Inc.