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. Such mutations are found in approximately 30% to 50% of metastatic colorectal tumors and are common in other tumor types. KRAS L19F has been previously reported in colorectal cancers, but its oncogenic and transforming potential was reported to be significantly lower compared to codons 12 or 13 KRAS mutants. The predictive and prognostic significance of this specific mutation in KRAS needs further elucidation. Results should be interpreted in conjunction with other laboratory and clinical findings.