The DNA sequence can be changed and damage by environmental agents such as mutagenic chemicals and certain types of radiation. The correction of DNA sequence errors in all types of cells is important for survival. DNA gene repair is an important way to repair this damage. One of DNA repair genes is the Ref-1 gene, However Ref-1 gene like other genes contains mutations which are found in different sites. In present study, whole blood was collected from 20 individuals distributed to two groups:- Ten lung cancer patients from various provinces and both gender and different age groups and Ten volunteers from healthy people as control group. DNA was extracted with ReliaPrep Blood gDNA Miniprep System and the results of Ref-1 by PCR gave positive for all samples. then analysis PCR product of 5 samples (patients and normal ), results compared with sequencing of original Ref-1gene in NCBI showed similarity between sequences of normal samples , while there were differences in the sequences of samples lung cancer patients Results of sequence analysis Ref-1 showed that were 11 mutation in 5 patients samples with gene Ref-1and show single mutation in some samples .Mutations lead to changes in the genetic code and in amino acids that is important reasons of an increase in the gene expression changes in Ref-1gene. . Web Site:  Web Site for Article