Although some familial cancer syndromes include biliary tract cancers (BTCs) (cancers of the gallbladder, intrahepatic and extrahepatic bile ducts, and ampulla of Vater), the few studies that have examined the relationships between family history of cancer (FHC) and BTCs have reported inconclusive findings. The objective of this study was to investigate the associations of FHC with risk of BTC in the Biliary Tract Cancers Pooling Project (BiTCaPP).