Colon cancer is the second most popular cause of death. is a important public health issue in developed countries for many years because of its frequency even with the screening and preventative strategies. It stills the second most common cancer in women and third prevalent cancer in men. Like other tumors. The most drug resistance subsets of cancer cells with high proliferation capacity are colon cancer stem cells (CCSCs) with self renewal and multi differentiation capacities. recently indicate that aldehyde dehydrogenase have role in drug resistance ALDH1 and ALDH2 have prognostic and clinicopathological value in colon cancer. The research involved 60 patients (both men and women) ranging in age from 35 to 65 years old. The samples taken from the Ministry of Health and Environment the medical city hospital’s histology laboratory, the Department of Education Laboratories. Colon cancer samples were divided into three groups: group I contained 20 samples from patients recently diagnosed with colon cancer, group II included samples from relapse patients who received chemotherapy but the tumor relapsed, and group III are resistance patient. This study was planned to evaluate the ALDH1 and ALDH2 as a marker for colon cancer stem cell.The percentage of the positivity forALDH1 and ALDH 2 shows in Figs. 3-7. The result are different between groups. Group one (new diagnosis patients) recorded low expression forALDH1 and ALDH2 about 33% forALDH1 and 48% forALDH2 in comparison with group II (relapsed patient) that represented moderate expression to the marker ( 63% and 72% forALDH1 and ALDH2, respectively). While, the higher expression was for group III (resistance patient) with percent of expression 80% and 90%