The main aim of the study is to assess expression levels of CDH1, FHIT, PTEN, and TTPAL genes in tumors and peripheral bloods of colorectal cancer patients in staged I-IV. Gene expression analysis of related genes were performed for tumor tissues and peripheral blood samples of 51 colorectal cancer patients and colon tissues and blood samples of 5 healthy individuals. The real-time-PCR reaction method was used for the analysis. Alteration of mRNA levels of related genes in tumor tissues of colorectal cancer cases was determined compared to control tissues. GAPDH and TBP were used for the normalization. While the mRNA levels of CDH1 decreased, the mRNA level of the FHIT and TTPAL genes increased in the tumor tissues. There was no PTEN gene expression difference in tumor tissues (total). The mRNA levels of the CDH1 and PTEN genes were increased while the mRNA levels of FHIT and TTPAL genes decreased in the blood (total). T he mRNA levels of the CDH1 gene decreased at each stage (I-IV) in the tumor tissues and increased at each stage (I-IV) in the blood. T he PTEN gene mRNA levels at each stage were controversial. The mRNA levels of the FHIT gene increased at stage I-II-III, decreased at stage IV in the tissues and decreased at each stage (I-IV) in the blood. The mRNA levels of TTPAL gene increased at each stage (I-IV) in the tissues and decreased at each stage (I-IV) in the blood.