MSI-H tumors are drove with molecular mechanism different from ordinary carcinoma, and thus the morphological features could be distinct. Particularly, MSI-H colorectal carcinoma has peculiar morphological characteristics, which are listed as one of the criteria to recommend MSI-testing. In this article, morphological characteristics and immunohistological detection of MSI-H colorectal cancer are reviewed, with contrasting to those of gynecological tumors.