To examine the roles of aromatic rings Tyr residues at positions 1 and 6 and Phe residues at positions 16, 17 and 19 of rat neuromedin U-23 (NMU-23) (Tyr-Lys-Val-Asn-Glu-Tyr-Gln-Gly-Pro-Val-Ala-Pro-Ser-Gly-Phe-Phe-Leu-Phe-Arg-Pro-Arg-Asn-NH(2)) for reducing food intake activity in male Wistar rats, two NMU-23 analogues, [Phe(4F)(16,17,19)]NMU-23 and [Tyr(Me)(1,6)]NMU-23, were synthesized by Fmoc strategy of manual solid-phase method. The synthetic NMU-23 showed reducing effect on food intake in rats. [Phe(4F)(16,17,19)]NMU-23 exhibited higher reducing food intake effect than that of NMU-23. On the contrary, [Tyr(Me)(1,6)]NMU-23 showed no reducing effect on food intake in rats than that of NMU-23.