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In recent years efforts to find bioactive compounds from live organisms especially marine animals have been increased. In the present study, the anticancer and cytotoxic effects of sea cucumber body walls (Holothuria leucospilota) were investigated. For this purpose, sea cucumbers were collected from Larak Island at depths of 10 to 30 m and extraction process was done with methanol and diethyl ether solvent which then concentrated by rotary evaporator (40℃) following lyophilization with vacuum freeze dryer. XTT method was used to investigate anticancer and cytotoxic effects of body wall extracts. The results showed that the methanolic extract could prevent proliferation of human oral epidermoid carcinoma cells (KB) at concentrations of 100 and 500 μg/ml. The diethyl etheric extract also could prevent proliferation of KB at 500 μg/ml concentration. Overall result showed that sea cucumber body wall had a strong cytotoxic effect on normal cell line (Human embryonic kidney cell [HEK]) which can be used as potent cytotoxic material. However these extracts did not show significant therapeutic value against KB cells.