Derivatives of dehydroabietic acid (1) having a hydrophilic moiety (such as amino, carbamoyl, carbamoyloxy, ureido, sulfamoyl, or sulfo) at positions 12 and/or 18 of the dehydroabietane nucleus were prepared and tested for antiulcer activity by means of antisecretory and antipepsin assays in rats. Among these compounds, the salts of 12-sulfodehydroabietic acid (62, 63, and 64) were found to exhibit remarkably high antipepsin activity without aldosterone-like activity.