The persimmon-bezoar, a kind of phytobezoar which is caused by overeating the astringent persimmon fruit, is generally understood to develop as a result of conversion of soluble shibuol, a specific constituent of the astringent persimmon fruit, into insoluble shibuol by the effect of gastric hydrochloric acid. How-ever, according to the present experiment, inasmuch as only soft flocks are formed when hydrochloric acid is added to a suspension of fine skin pieces of the persimmon fruit, such an explanation seems to be insufficient. The authors ap-plied their basic theory of solidification of colloidal substances in living organism (Tohoku J. exp. Med., 1964, 84, 259) to this problem and succeeded in preparing in vitro a bezoar-like solid concrement using persimmon fruits, which proved the propriety of this theory in this case.