The vascular changes of the pulpal vessels in experimentally induced pulpotomy in dog tooth were investigated using microcorrosive resin casts technique and scanning electron microscopic examination. The pulpal tissues of the permanent mandibular molars were amputated and then dressed with calcium hydrate. At one to eight weeks after pulpotomy, the experimental teeth were prepared for resin casts of pulpal vessels with hard tissues. One week after pulpotomy, a concave region, which was supposed to be due to the compression by the calcium hydrate, was found in the newly formed pulpal vascular network. Around the concave region was a flat, dense capillary network. In eight weeks, the thick dentin bridge was formed in close proximity to the amputated pulpal surface. The vascular network just beneath the dentin bridge changed into similar features in the three layers of the normal pulpal vascular architecture, which are (i) terminal capillary network (TCN), (ii) capillary network (CN), and (iii) venular network (VN) and which distributed in the superficial layer of the pulpal vessels.