All reproductive age women menarche - age 21, undergoing chemotherapy with agents known to affect ovarian function that have a follicle stimulating hormone level (FSH) less than 20 mIU/L will be offered enrollment. We define premature ovarian failure as the development before age 40 years of greater than 4 months of amenorrhea or menstrual irregularity, associated with two serum FSH levels in the menopausal range (sampled at least 1 mo apart).