Clinical and laboratory data from Western countries suggest that pregnant women are at an increased risk for severe illness and complications associated with 2009 pandemic influenza A (H1N1). However, previous data among Korean women suggested a less severe outcome. In this study performed at a single referral center in Korea, rates of admission, pneumonia, intensive care unit admission, and death related to 2009 pandemic influenza A (H1N1) were significantly higher in 33 pregnant women than in 723nonpregnant women of reproductive age (p＜0.05 each). We report two cases of 2009pandemic influenza A (H1N1) in pregnant Korean women who were admitted to the intensive care unit because of severe pneumonia that led to maternal and fetal death in one of the patients. This case series suggests that pregnant Korean women were also at increased risk of severe illness and complications during the 2009 pandemic influenza A (H1N1) outbreak.