Received March 02, 1997
Accepted May 17, 1997

The authors describe the different methods for obtaining human gonadotropins of higher purity, ranging (rom those isolated by a urinary extraction process to those elaborated by genetic engineering. Ovarian physiology is discussed, especially in terms of the role of luteinizing hormone. Ovarian stimulation with gonadotropins in special situations such as micropolycystic ovarian syndrome is also discussed. Protocols of ovarian stimulation for "in vitro" fertilization are described in detail. Ovarian hyperstimulation syndrome is evaluated in terms of physiopathology, prevention and treatment. Finally, the problem ofmultiple pregnancies is considered.