Luteinizing hormone-releasing hormone(LHRH) agonists as antitumor agents for hormone-dependent tumor have been on the market for about ten years, while the LHRH antagonists that have been developed furthest are still in clinical trial. Significant progress has been made in searching for LHRH antagonists with high activity, low histamine releasing, good aqueous solubility. Smaller linear or cyclic peptides and peptidomimetics showed antagonistic activity both in vitro and in vivo. The βⅡ-turn in the central tetrapeptide and the N-terminal tripeptide segment of decapeptide LHRH antagonists play an important role in receptor binding.