This work was undertaken in order to evaluate retrospectively the relative efficacy of ovulation induction by menotrophins and that of in-vitro fertilization and embryo transfer (IVF-ET) in the treatment of unexplained infertility. These two treatments were compared between two groups of patients: 87 couples undergoing 446 cycles of ovulation induction by menotrophins (group A) and 72 couples undergoing 108 cycles of IVF-ET (group B). A total of 30 and 20 pregnancies were achieved in groups A and B for a rate of 34 and 28% per patient, respectively. A similar cumulative pregnancy rate (CPR) was achieved for three cycles of ovulation induction (23%) and one cycle of IVF-ET (22%). The cumulative live birth rate (CLBR) in group A was 22% after three cycles and exceeded that of one IVF-ET cycle (17%). It is concluded that menotrophin treatment in unexplained infertility is highly beneficial and should precede an IVF attempt.