The complement system is a cascade of multiple proteins that have been known to mediate inflammatory response. This tightly regulated system has been recognized to play a role in adaptive immunity via humoral and cell-mediated processes. There is evidence from animal and human studies that the complement system is involved in various outcomes of solid organ transplantation. Most of the studies have been done in the field of kidney transplantation. In this paper, we review the studies looking at lung transplantation. The complement cascade appears to have a prominent role in mediating lung allograft damage in the setting of ischemia-reperfusion injury, humoral rejection, as well as chronic allograft dysfunction. In this review, we look at the available data regarding the role of complement in these outcomes and propose some ideas about future direction of research in this field.