The purpose of this investigation was to study histopathological chronology and differences of the proprietary pulpcapping agents. One hundred eighty molars from thrity rats (Srague-Dawley species), weighing about 130gm, were divided into six groups. Cavities were prepared in their maxillary molars under intraperitoneal anesthesia with Secobarbital. The cavities in the right first and second molars were filled with Dycal$^{(R)}$ and the left ones were with Cavitec$^{(R)}$. Each group of rats were sacrificed at the intervals of 1, 3, 5, 7, 14 and 21 days following operation. The rats were decapituated, and the jaws were fixed in 10% neutral buffered formalin. Then the specimens were decalcified, embedded in paraffin or celloid, and sectioned at 6-8 ${mu}$ in thickness through the cavities included and pulp mesiodistally. They were stained with Hematoxylin-Eosin and examined by lightmicroscope. The results were as follow: 1. The pattern of pulp healing was dependent upon the presence and character of the pulpcapping agents above. 2. Dentin bridge formation as a sign of pulp healing occurred in the 14 days after operation. 3. Dycal$^{(R)}$ reparation appeared to favor pulp bealing rather than Cavitec$^{(R)}$ preparation. 4. In the odontoblastic layer and pulp tissue specific vaculoes were showed at the 3, 5 and 7 days of the Dycal filling.