A prospective, randomized, open, multicentre (n = 3) study was conducted to compare the efficacy and efficiency of a fixed daily dose of 150 IU (3x50 IU) recombinant follicle stimulating hormone (recFSH, Puregon((R))) and 225 IU (3x75 IU) highly purified urinary FSH (uFSH-HP, Metrodin-HP((R))) in women undergoing ovarian stimulation prior to in-vitro fertilization treatment. A total of 165 women were treated with FSH, 83 subjects with recFSH and 82 subjects with uFSH-HP. In the recFSH group a mean number of 8.8 oocytes were retrieved, compared with 9.8 in the uFSH-HP group (not statistically significant). In the recFSH group, a significantly lower total dose was required compared to the uFSH-HP group, 1479 versus 2139 IU, respectively (P < 0.0001; 95% confidence interval -747 to -572). Treatment with recFSH resulted in a significantly higher embryo development rate (69.6 versus 56.2%; P = 0.003) and more embryos accessible for the embryo freezing programme (3.3 versus 2.0; P = 0.02) compared to uFSH-HP. The vital pregnancy rate per cycle started was 30.2 versus 28.3% in the recombinant and urinary FSH group, respectively. It is concluded that treatment outcome of a fixed daily dose of 150 IU recFSH is comparable to a fixed daily dose of 225 IU uFSH-HP. However, a significantly lower total dose was needed in the recFSH group (nearly 700 IU less).