PIP: Estrogenic and antiestrogenic properties of E-492, a nonsteroidal compound (3 methyl-4'-(beta-pyrrolidinoethoxy)-2,3-diphenyl propiophenone), were assessed on the basis of ponderal, histologic, and biochemical changes in the uterus, cervix, and vagina of ovariectomized adult rats. This compound was studied at its maximum effective antifertility dose of .5 mg/kg/day for 5 days. Estradiol-dipropionate (EDP) was studied at a dose of 1 mcg/kg/day. EDP and E-492 separately increased the weight of the 3 genital accessories. Histologically, the organs presented an infantile condition characterized by atrophic epithelia, compact stroma, and inconspicious muscularis. The uterine glycogen level was raised by EDP (p less than .01) but not by E-492 (p greater than .05). Lactic acid was increased by EDP in all target organs (p less than .01) and by E-492 in the uterus and vagina (p less than .01) but not in the cervix (p greater than .05). Combined therapy antagonized EDP effect at the uterine and vaginal levels. Alkaline phosphatase was enhanced by EDP in all 3 organs (p less than .01) and by E-492 in the uterus and cervix (p less than .01). These results indicate that on the basis of changes in weight and histology, E-492 has both estrogenic and antiestrogenic potencies.