KRAS is a gene that encodes one of the several proteins in the epidermal growth factor receptor (EGFR) signaling pathway that is important in the development and progression of cancer. KRAS can harbor oncogenic mutations that yield a constitutively active protein. KRAS mutations are common in both extrahepatic (40-49%) and intrahepatic (24-27%) cholangiocarcinomas. Mutations in the KRAS gene may indicate poor prognosis and drug response with therapies targeted to EGFR in some settings. Of note, RAS mutations sensitize tumors to MEK inhibitors. However, this should be interpreted in conjunction with other laboratory and clinical findings.