Allylthio group of allicin and other organosulfur compounds which are isolated from garlic is considered as a pharmacophore, a key structure component of the molecule which is responsible biological activities. In the foregoing studies various 3-allylthio -6- alkoxypyridazine derivatives (K- compounds ) and 3-allylthio -6- alkylthiopyridazine derivatives(Thio-K-compounds) were synthesized and their biological activities were tested in vivo. They showed good hepatoprotective activities on the carbon tetrachloride-treated mouse and aflatoxin Bl-treated rat and chemopreventive activities on bepatocarcinoma cells in rat as expected. Now 3-allylthio-6-heterocyclylalkylaminopyridazine derivatives that the oxygen atom at 6-Position of 3-allylthio-6-alkoxypyridazine is replaced by nitrogen (N) were synthesiz ed and their activities were tested in vitro against SK-Hep-1 human liver cancer cells. They showed good chemopreventive activities on hepatocarcinoma cells.