Abstract: Peritoneal metastasis is very common in colorectal cancer and often indicates bad prognosis.The peritoneum, which contains an abundant supply of blood and specific types of resident and migrating cells, lines the surface of the abdominal wall and coversthe abdominal organs.The combination of cells, extracellular matrix, and local unique physicochemical composition of the abdominalcavity provide a complex and relatively stable peritoneal microenvironment.The cells in this environment can be induced by cancercells to be involved in tumor growth, invasion, and peritoneal metastasis.This review summarizes the major cellular components involved in the peritoneal microenvironment.