Trichomonas vaginalis parasitizes in human genitourinary tract. The protozoon adhering to target cell plays a critical role in its contact-dependent cytotoxicity. The enzymes synthesized by T.voginalis can hurt vaginalis epithelial cells (VECs) directly. The focal immune reaction in the location parasitized by the parasite may provide an immunologic protection. Meanwhile, inflammatory factors and immune cells may aggravate the situation. In general, the T. vaginalis-induced contact-dependent cytotoxicity is a result of the involvement of some molecular and chemical factors.