Abstract: Objective: To investigate the KRAS gene mutation features in lung and gastric cancers and their relationship with clinicopathologic characteristics. Methods:A total of 128 lung cancer and 115 gastric cancer patients were included. Polymerase chain reaction amplification and DNA sequencing were conducted to detect mutations in exon 2 of the KRAS gene. Results: The mutation frequency of KRAS was different in lung and gastric cancers; however, it did not show any statistical significance (6.3% vs.4.3%,P>0.05). The KRAS codon 12gene mutation ranks the first in both types of cancer. No significant correlation was observed between the prevalence of KRAS mutations and patient's age and gender. KRAS gene mutation rate was higher in lung adenocarcinoma than in non-adenocarcinoma, such as squamous cancer (10.7% vs.0% ,P<0.05). Conclusion:No correlation was found between the KRAS gene mutation and the sex and age of lung and gastric cancer patients in Jiangsu Province. The rate of KRAS mutation was low. KRAS gene mutation rate was relatively higher in lung adenocarcinoma patients; thus, the mutation status of the KRAS gene should be evaluated be-fore undergoing EGFR-TKI therapy.