The aim of this study was to determine the effectiveness of a new highly purified urinary FSH. A total of 60 in vitro-fertilization (IVF) patients, undergoing embryo transfer (ET) for the first time, were randomly allocated into two groups: Group A (n = 30). Subcutaneous administration of urinary follicle-stimulating hormone (FSH, Fostimon 75, A.M.S.A., Italy). Group B (n = 30). Subcutaneous administration of urinary follicle-stimulating hormone (FSH, Metrodin 75 HP, Serono, Italy). Statistical analysis was performed using the chi-square test, p < 0.05 was assumed as significant. This prospective randomized clinical study in an IVF-ET program showed that both drugs were equally safe and effective. Except for the number of the high quality embryos (3.16 vs 2.9; p = 0.03) the two groups did not differ in stimulation parameters or clinical pregnancy rates per attempt and per transfer. On the other hand, a mean number of 3.56 vs 2.18 embryos were cryopreserved in group A and in group B, respectively, as a result of the high number of mature oocytes and high quality embryos. When frozen embryos cycles were included, the difference in pregnancy rate became significant.