Primary graft dysfunction (PGD) is a form of early lung graft dysfunction that is a major cause of early morbidity and mortality following lung transplantation. Survivors of PGD have decreased long-term lung function and an increased risk of developing bronchiolitis obliterans syndrome (BOS), a manifestation of chronic graft dysfunction. This article reviews the current definition, contributing factors, and guidelines for grading clinical PGD, as well as controversies surrounding them. The current literature examining clinical risk factors for PGD is summarized, as are studies exploring molecular and biochemical markers for PGD prediction and severity. Studies examining the short-and long-term effects of PGD on lung transplant outcomes are reviewed. Lastly, we highlight the emerging concepts in lung transplantation that will potentially impact PGD incidence and outcomes.