On June 11, 2009, the World Health Organization declared the first influenza pandemic in more than 40 years. In less than 2 months, the novel 2009 H1N1 influenza A virus had spread from Mexico and the United States to many other countries of the world. Oseltamavir and zanamivir have been used to treat hospitalized and at-risk patients infected with 2009 H1N1 influenza A infection. On October 23, 2009, the Food and Drug Administration issued and Emergency Use Administration for peramivir, an unapproved neuraminidase inhibitor, allowing the drug to be administered to adult and pediatric patients with suspected or confirmed cases of H1N1 influenza A virus. Patients had to have either a refractory case and/or could not tolerate oral or inhaled antiviral medications. This article will review the mode of action, pharmacokinetics and pharmacodynamics, clinical effectiveness, adverse events, and resistance pattern of peramivir and will summarize the Emergency Use Administration issued by the Food and Drug Administration.