A new flexible protocol for the induction of recipient endometrial cycles is presented. For stimulation of endometrial growth, a fixed dose of conjugated estrogens, 3.75 mg/d was employed. The duration of the proliferative phase varied from 9 to 14 days, thus being adjusted to match the length of the follicular phase of the donor. Embryo transfer was performed on the fifth day of progesterone administration. Four term pregnancies resulted from 12 treatment cycles. In the conception cycles, the hormonal support was continued until the luteal placental shift occurred, regardless of gestational age.