The production of recombinant gonadotropins is independent of urine co
llection. They have a high specific activity and a better batch to bat
ch consistency than urinary gonadotropins. In our IVF programme 62 nor
mo-ovulatory patients less than 38 years old, with tubal or idiopathic
infertility and normal sperm, were treated by r-FSH and randomized in
to four groups : with or without LHRH agonist, step-up or step-down st
imulation. The overall results were higher in the agonist groups, but
did not reveal any significant difference between step-up and step-dow
n stimulation.