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. The frequency of the KRAS gene mutations in intraductal papillary mucinous neoplasms (IPMNs) varies from 38.2% to 100%. There appears to be no significant difference among the incidence of KRAS mutation in the various grades of dysplasia: 87% in low-grade, 90.2% in intermediate grade and 70.7% in high-grade dysplasia. This mutation is considered to be an early event in the neoplastic transformation of IPMNs. KRAS mutations have the highest frequency in the pancreatobiliary subtype (100%) and the lowest frequency in the intestinal subtype (46.2%). Studies demonstrate that KRAS mutations in different tumors may have various biological, prognostic, and possibly therapeutic implications in some settings.