Disclosed herein are peptide analogs of the luteinizing hormone releasing hormone (LH-RH) which are very potent antagonists of LHRH. These analogs are even active when administered through the oral route. They differ in structure from LH-RH by having other amino acid residues at the positions 1 and 2, by the presence of a basic amino acid residue at position 6 and by the optional presence of other amino acid residues at the positions 3 and 10.
