Abstract: MicroRNAs (miRNAs) are non-coding single-stranded RNAs of about 22 nucleotides that regulate a variety of cellular processes including proliferation, differentiation, and apoptosis. Recent studies suggest an important role for miRNAs in the initiation and progression of human malignancies. Some miRNAs may function as oncogenes or tumor suppressors. Changes in the expression of many miRNAs have been observed in colorectal tumor tissues and cell lines. Some of them are significantly downregulated, such as miR-143, miR-145, let-7, and miR-34a, and some are upregulated, such as miR-31and miR-21. Previous studies have demonstrated that transfection of miR-143 and miR-145 precursors into human colorectal cancer cell lines leads to significant growth inhibition in a dose-dependent manner. The miRNA expression profile has relevance to the biological behavior and clinical stage of colorectal cancer. It has been reported that the upregulation of miR-31 is significantly higher in stage IV colorectal carcinoma samples than in stage II colorectal carcinoma samples. There is a notable discrepancy in the expression profile between colorectal cancer cell lines and clinical samples. The miRNA expression profile in colorectal cell lines may not be suitable to infer miRNA expression in clinical samples. MiRNAs such as miR-143, miR-145, and miR-34a have the potential of inhibiting cell growth and proliferation. Downregulation of these specific miRNAs in colorectal cancer cells contributes to overgrowth and out-of-control proliferation, which may be fundamental steps for colorectal cancer initiation. Moreover, some chemotherapeutic drugs can affect the expression of colorectal cancer-related miRNAs. The expression of miR-34 in colorectal cancer cell lines is increased after Adriamycin treatment. It has been inferred that miRNAs may be involved in the mechanism of chemotherapeutic drugs. Identification of the precise functions of miRNAs will further develop the etiological and pathological theories of colorectal cancer and suggest a promising future therapeutic strategy. We review recent advances in the research of colorectal cancer-related miRNA.