Between February 1987 and February 1989, 13 women with primary ovarian failure due to gonadal dysgenesis were treated with embryo transfer following ovum donation in 22 cycles. Eight pregnancies were obtained (36.7% per transfer); four births of normal children, two spontaneous abortions and two other pregnancies currently ongoing (between 5 and 8 months). An association of percutaneous oestradiol, oestradiol valenate and intravaginal progesterone was used as hormone substitution and embryo transfer was only performed following assessment of the endometrium during a previous cycle. Apart from the day of embryo transfer, which was the same for all patients (the 2nd day after initiation of progesterone) various prognostic factors were analysed. These were the type of gonadal dysgenesis (45 XO, 46 XX or 46 XY), the number of embryos replaced, whether they had been frozen, whether the egg donor was anonymous and finally the influence of the hormone substitution protocol. Only the number of embryos replaced and the substitution protocol seemed to influence the implantation rate. The other parameters, and in particular the type of gonadal dysgenesis, seemed to have no effect on the results. The pregnancy rate per transfer was 30% for 45 XO (10 transfers), 25% for 46 XX (eight transfers) and 75% for 46 XY (four transfers).