The role of KRAS gene was investigated in manifestation of colorectal cancer in Iraqi patients. A total 40 blood samples were collected during October 2016 to January 2017 from AL-Amal Hospital in Baghdad and 20 blood samples from healthy subjects served as control. Blood samples were collected from subjects of 40-70 years old for both patients and control. The study found that age group 61-70 years old were more susceptible to colorectal cancer with ratio of 40% more than younger individuals involved in this study with higher frequency in males with 75.5% than females who show 49.5% (p>0.01) when both compared to the same gender. DNA extracted from positive cancer samples and control were subjected to specific PCR amplification using 10 specifically designed primers for this study to amplify KRAS gene exons. DNA sequencing for the resulting amplicons showed the presence of significant genetic change that included substitution and insertion, causing 15% frame shift and 85% missense changes at positions 5920, consequently led to sever disruption in KRAS function.