The present investigation has been undertaken to understand the mechanism of implantation process, by demonstrating the role of ovarian steroids in the differentiation of uterine endometrium for implantation. In particular, an attempt was made to examine the activity of alkaline phosphatase (ALP) in the either luminal, stroma or endometrium tissue sites under the pseudopregnant state induced by ovarian steroid hormones. Attempt was also made to demonstrate the correlate function of ovarian steroids with the cAMP concentration and prolactin level. The higher activity of ALP in the uterine endometrium was observed on day 3. However, the higher activity of ALP in the stroma and epithelium was observed on Day 6. This study, therefore, clearly demonstrates that progesterone is consecutive effect in stroma differ entiation. The cAMP concentrations on Day 3 treated with E or P was lower than those of control. On the other hand concentration on Day 6 treated with hormones was increased than those of control. It is, therefore, concluded that the concentration of cAMP in the uterine tissue undergoing differentiation is decreased. The prolactin level of the treated groups was the lower levels than those of the control groups. It is indicated that there is no effect of ovarian steroid hormone on the prolactin synthesis in this pseudopregnant state.