Ovum donation and in-vitro fertilization (IVF) surrogacy can help couples with difficult infertility problems achieve pregnancy. Most centres using oral oestrogens and oestradiol patches report pregnancy rates in the range of 30% per cycle. Parenteral oestradiol valerate has pharmacological properties that make it an attractive option for preparing the endometrium in the recipients undergoing these procedures. When the egg providers were under age 35 years, and using oestradiol valerate in the recipients, we achieved a 61% clinical pregnancy rate in 62 cycles. These improved results suggest that parenteral oestradiol valerate should be used to prepare the endometrium in recipients, and that the hormonal milieu of the endometrium plays an important role in the higher implantation rates obtainable in ovum donor and IVF surrogate cycles.