Effect of different hormonal stage on incorporation of (1-14C)palmitic acid (PA) into the uterine phospholipids (PL) has been studied. Virgin female Wistar rats were divided into the following groups: ovariectomized 7 and 28 days, untreated; ovariectomized received a single injection of estradiol, ovarietomized received a single injection of progesterone (after estradiol-priming), intact cycling females received pregnant mares serum gonadotrophin, intact cycling females injected human chorionic gonadotrophin after PMSG-priming. Uteri horns were incubated a buffer containing 14C-PA. Lipids were extracted and fractionated using thin-layer chromatography. Estradiol increased PL-content, incorporation of (1-14C)-PA into the PL, while progesterone inhibited E-dependent effect, Gonadotrophin-induced ovulation provoked increase in uterine PL-content and remained a stimulatory signal for incorporation of (1-14C)-PA.