The aim of this study was to evaluate the clinical efficacy and safety of a new urinary follicle stimulating hormone (FSH) preparation (Fostimon) in patients undergoing in vitro fertilization-embryo transfer or intracytoplasmic sperm injection. Metrodin HP was adopted as a reference drug, as its purity and therapeutic efficacy are well known. Sixty normo-ovulatory patients aged 18-38 years with normal basal FSH and body mass index < 25 kg/m2 were selected for the study. After gonadotropin releasing hormone analogue pituitary desensitization, patients were randomized to receive either Fostimon or Metrodin HP at the initial dosage of 225 IU for 6 days. Thereafter, the dosage was tailored according to the ovarian response. Both drugs were administered by the subcutaneous route. The primary end-points were: number of follicles larger than 15 mm, levels of 17 beta-estradiol on the day of human chorionic gonadotropin (hCG) injection and number of oocytes recovered. The secondary end-points were: number of FSH ampules used, day of hCG injection and pregnancy rate. FSH kinetic curves were calculated during the treatment period with both products. Safety was evaluated by pre- and post-treatment blood biochemistry and hematology, and recording all side-effects. Local tolerance was investigated at each visit. None of the parameters evaluated showed a statistically significant difference between the two groups. Local tolerance was always recorded as good/excellent by both the patients and the physician. In conclusion, Fostimon proved to be an effective and safe drug for assisted reproductive cycles.