A new series of LH-RH [luteinizing hormone releasing hormone] analogs [antineoplastic-drugs] containing an Azgly10 [azaglycine residue in position 10] modification and having potent agonist properties were given in high concentration to intact female rats. Plasma LH [luteinizing hormone] and FSH [follicle stimulating hormone] were raised to extremely high levels after 14 days administration of the compounds (5.0 and 0.5 .mu.g/rat twice daily), but plasma estradiol concentrations were reduced to those in ovariectomized rats. The weights of the ovary and uterus were also markedly reduced, suggesting that these compounds are, on this treatment regime, producing the effects of chemical castration.