The availability of recombinant FSH and LH opens an opportunity to individualize ovarian stimulation. While the need for FSH is universal, a question remains whether exogenous LH is beneficial. Previous research on adding LH to an unselected group of patients failed to demonstrate any advantage. Indeed, it may seem presumptuous to expect that all patients will respond in the same manner. Recent studies hint that LH supplementation should be individualized. These studies indirectly suggest that the changes in LH concentration may be more important than the concentration per se. The growing follicle, and particularly oestradiol biosynthesis, may be sensitive to decreases in LH concentrations. The challenge is to identify the patient whose LH will drop during stimulation. This individualized approach will assure that supplemented LH will only be given to those who need it.