The pharmacological effects of hydrocooked(110oC, 5 hours) extracts of Bastard halibut have been investigated. All of the hydrocooked extracts showed the measurable contractile effect on the isolated rat duodenum and decreased the normal blood pressure in anesthetized rat. The hydrocooked extracts also exhibited a dose dependent relaxation on the isolated rat aorta precontracted with phenylephrine. Only RM 60 fraction of these extracts had the cytotoxic effect against MCF7 cell(human breast adenocarcinoma cell line), but the other fractions showed neither antibacterial activity nor antitumor activity. Although fish extracts fed group of rat maintained their original body weight, there were no notable changes in the hematological parameters, except that the levels of high density lipoprotein was significantly increased. These results suggest that the hydrocooked extracts of bastard halibut may contain a variety of bioactive materials.