The histopathological study was made to investigate the pulp reaction of "Hipol". The toxicity against the pulp tissue was compared with the "Zinc-Oxide-Eugenol Cement." A total of 36 cavities of healthy prmanent teeth of the 3 dogs were chosen and filled with the experimental filling materials without base. The teeth were prepared at 3 intervals; a week and two, three weeks as a result of this study. 1) Both "Hipol" and "Adaptic" showed very severe to moderate pulp reactions in the all of the filled teeth. 2) There was little difference between "Hipol" and "Adaptic" in the severity of the pulp reaction. 3) After 3 weeks, the teeth filled with "Hipol" and "Adaptic" showed more or less recovery phenomena. The teeth filled with "Zinc-Oxide-Eugenol Cement" showed marked recovery phenomenon. 4) There was little difference in the histopathological result between "Universal" group and "Catalyst" group.