Advances in cancer therapy have improved the long-term survival of young patients suffering from malignancies. The adverse effects of the treatment, however, are sterility and loss of gonadal function especially in females. If preservation of fertility in males by sperm freezing is already established, for young women undergoing cancer treatment the availability of preserving the gonadal function and fertility has just begun. Diseases commonly treated with radiation or chemotherapeutic agents in young women are breast cancer, lymphoma, leukemia, blood dyscrasia, glomerulonephritis, lupus erythematosus, and rheumatoid arthritis.