The aim of present study was to determine the distributions of proliferating cell nuclear agent (PCNA) and Caspase-3 (Cas-3) and their possible roles in implantation and decidualization during early pregnancy at immunohistochemical level. The tissue samples from pregnant animals between gestational days 1-5 were incubated by PCNA and Cas-3 anti-bodies and the obtained results were evaluated quantitatively. It was observed that PCNA immunoreactivity in uterine luminal epithelium and glandular epithelium reduced as from day 2 of gestation and disappeared as from day 4 of gestation. PCNA staining intensity in stromal cells and myometrium increased gradually with progressing gestation. While Cas-3 immunoreactivity was strongly detected in luminal and glandular epithelium throughout the whole gestational period, its reactivity markedly increased as from day 3 of gestation. In conclusion, it may suggest that the blastocyst implantation induces the uterine luminal epithelial cell death and stromal cell proliferation around the embryo in the uterus.