The current work attempts to investigate the molecular basis of colorectal carcinoma of Iraqi patients. This molecular based study was conducted using retrospective samples of colorectal cancer patients to investigate the role of p53 ,c- Myc bcl-2 and bax genes in carcinogenesis and anti carcinogenesis, using polymerase chain reaction followed by DNA sequencing to detect the mutations in the exons 5,6,7,8 and 9 of p53 gene, immunohistochemical (IHC) used to diagnose the expression of p53 and c-Myc and in situ hybridization (ISH) assay using a specific biotin labeled probe for bcl-2 and bax genes to detect its mRNA expression level. These genes known to play a pivotal role in cell cycle regulation as well as apoptosis in order to understand the underlying mechanisms for such association between these genes and colorectal carcinoma. Thirty Five colorectal cancer patients and 12 control subjects (resection margin) were enrolled in this study. Colorectal cancer patients were 14women and 21 men with a mean age of 57.5 years (range between 27 and 75 years). For each of the selected patient, paraffin-embedded blocks were retrieved. Histopathological data including tumor stage, degree of differentiation in addition to the age and sex for colorectal cancer patients were recorded. Blood samples were obtained from 15 control subjects (9 men and 6 women) with a mean age of 45 years, range between 20 and 62 years to be used for DNA extraction that were used in p53 mutation detection by PCR and DNA sequencing, as a positive control. DNA was successfully extracted from the formalin fixed paraffin embedded tissue and blood samples of the healthy people for p53 exons amplification by PCR and then mutations detection. The extracted DNA was used successfully in amplification of p53 exons 5,6,7,8 and 9 using two sets of specific primers, ie two primer pairs for each exon. Five primer pairs were selected to amplify the exons 5-9 after optimization the amplification conditions. The PCR products of the five exons for each of the amplified samples were purified and sent for DNA sequencing analysis. The preliminary results of mutations detection in the p53 exons for the colorectal cancer patient showed the presence of mutations for the samples that investigated till now, further analysis and alignment need to perform later to detect the common types of mutations in CRC patients in Iraq.