Ocean organisms live in competitive environments that demand the production of poisons and toxins . In some cases, these substances have been used in the pharmaceutical industry for human disease treatments . Most fish poisons generally have potent cytolytic activity, probably through cardiovascular and neuromuscular effects . In the case of marine stingrays, the injuries made by their tail venom apparatus are caused by the mechanical penetration of their sting and a subsequent venom release . This study focused on the evaluation of substances with cytotoxic activity in the epithelium that covers the venom apparatus from the marine stingray Hypanus dipterurus . To demonstrate the above, the hemolytic, proteolytic and cytotoxic capacities of H. dipterurus epithelium substances were determined . Discs impregnated with epithelial extract were used on blood agar plates . The proteolytic activity was analyzed using casein as substrate and for gelatin the liquefaction activity test . To determine the cytotoxicity degree of the extracts, the proliferation and cell viability MTT bioassay was implemented on human cervical carcinoma cells (HeLa). The results showed that no hemolytic or proteolytic activity existed against casein associated with the epithelial extract, but gelatin hydrolysis and cytotoxic activity against the HeLa cell line were observed . This study concludes that the substances found in the epithelium covering the H. dipterurus stingray venom apparatus are a mixture of various proteins, among which, glycosylated anionic proteins represent a potential source of molecules with cytotoxic and hydrolytic activity.