BACKGROUND: 2009 H1N1 influenza A disproportionately affected pregnant and postpartum women compared with the general population, with higher rates of hospitalization and severe illness. We present a case of the use and pharmacokinetics of intravenous peramivir in the treatment of a patient with severe influenza. CASE: A 28-year-old woman at 37 weeks of gestation presented to the hospital with severe respiratory symptoms. 2009 H1N1 influenza reverse transcriptase polymerase chain reaction returned positive results and intravenous peramivir was started. She showed rapid improvement and was discharged 29 days after admission. CONCLUSION: The pharmacokinetic parameters in this patient were unexpected because the clearances occurred more quickly than in phase I trials. These differences highlight the need for additional pharmacokinetic reporting of peramivir in pregnant and postpartum women.