Introduction: Colorectal cancer is the second commonest cancer arising in the world. Colorectal cancer can present with an array of symptoms and approximately 35–48% of patients diagnosed with colorectal cancer have experienced rectal bleeding. Objectives: The main objective of the study is to analyse the role of gut microbiota alteration in colorectal cancer and its clinical implications. Material and methods: This descriptive study was conducted in King Edward Medical University during June 2019 to November 2019. Several studies have shown that numerous bacterial species appear to be associated with the pathogenesis of CRC and recent studies have provided a mechanism for the participation of gut microbiota in the progress of CRC. Results: The median age of the patients was 56 years (range: 20–86), and 73% were male. Most patients were married [85.6%], and more than half of the participants were high school educated or higher [77.8%] and unemployed 52.8%. The differences in microbial community abundance between the two groups were examined by statistical methods, and the significance of the differences was evaluated by FDR (false discovery rate). We screened out the species that caused the difference in the composition of the two groups of samples.