Numerous analogues of N-phenethyl-2-(isochroman-1-yl)-1-methylethylamine (3b), previously found to have inhibitory activity against aspirin-induced ulcer and no gastric antisecretory activity, were prepared and examined for gastric antisecretory activity and inhibitory activity against aspirin-induced ulcers in rats. It was found that a basic amine moiety is required for the antiulcer activity. Replacement of the isochroman ring of 3b by a thioisochroman, chroman, or tetralin ring resulted in a drastic change in the antiulcer activity. Among them, the chroman analogue N-phenethyl-2-(chroman-4-yl)-1-methylethylamine (32b) was found to have the most potent antiulcer activity, comparable with that of 3b.