This case illustrates the possibility of achieving a pregnancy and birth when elevated progesterone concentrations (> 4 ng/ml) are present during the follicular phase (from 6 days before human chorionic gonadotrophin injection) of a gonadotrophin-releasing hormone agonist/menotrophin cycle for in-vitro fertilization (IVF). The present patient underwent three IVF/embryo transfer cycles in which progesterone concentrations were repeatedly increased from the midfollicular phase onwards. A pregnancy was achieved after the first IVF attempt but ended in a miscarriage in the 19th week of gestation. During the second IVF attempt an endometrial biopsy taken on the day of oocyte retrieval revealed an endometrial advancement of 2 days. A successful pregnancy and birth was again achieved after the third IVF attempt although progesterone concentrations were considerably increased from 6 days before the ovulatory stimulus.