Proprotein convertase subtilisin/kexin type 9 (PCSK 9) is a key regulator of cholesterol homeostasis acting via degradation of the low density lipoprotein (LDL) receptor. Loss of function PCSK 9 mutations result in very low LDL cholesterol serum levels and protection from cardiovascular disease whereas gain of function mutations increase serum LDL cholesterol. Based on in vitro and in vivo data antibodies targeting PCSK 9 have now emerged as a novel treatment option in patients with cardiovascular disease. This review briefly summarizes the biochemistry and function of PCSK9 and the results from recent phase II trials.