Abstract: Objective To investigate the expression difference of microRNAs in colorectal tubular adenoma, tubulovillous adenoma and colorectal cancer. Methods Real time-polymerase chain reaction was used to analysis the expression level of miR-1, miR-9, miR-31, miR-135a, miR-137 and miR-145 between colorectal tubular adenoma (n=44), tubulovillous adenoma(n=16), colorectal cancer(n=20) and paired paracancerous normal colorectal tissues. Results Compared with paired paracancerous normal colorectal tissues, colorectal tubular adenoma had decreased expression of miR-1, miR-9, miR-137 and miR-145 as well as increased expression of miR-31 and miR-135a. Colorectal tubulovillous adenoma had decreased levels of miR-1, miR-137, miR-145, as well as increased levels of miR-9, miR-135a, and miR-31. Colorectal cancer had the expressions of miR-1, miR-9, miR-137 and miR-145 decreased while the expression of miR-135a and miR-31 increased. Conclusion The differential expressions of microRNAs suggested that miRNAs participate in the development of colorectal adenoma and cancer.