Background: Colorectal cancer is a common disease in the world as well as in Vietnam. K-RAS gene mutations in colorectal cancers is a topical question and currently be interested by researchers in the World. However, in Vietnam, this is not much studied. Therefore, the objective of this research: Compare the K-RAS gene mutations with images endoscopic in colorectal cancer patients at Hai Phong Viet-Tiep hospital. Subjects and methods: crosssectional study described in 79 colorectal cancer patients. To determine the mutation of K-RAS gene by technical sequencing gene, performed in the center for gene and protein research of Hanoi Medical University. Results and conclusions: The mean age of patients was 61,7 + or - 12,3 (the highest age is 81 and the lowest was 21), most patients met at ages 61-70 (32,9 percent), ratio male/female was 1,55/1. Size of tumor has relationship with K-RAS gene mutations (p 0,05). Position, images of tumor can not see the relationship with K~RAS gene mutations (p 0,05).