Abstract: Human follicular gonadotropin releasing peptide(hF-GRP)and fifteen analogshave been synthesized manually by stepwise solid-phase procedure.For some shorter sequences(lessthan ten residues)0.5 mol/L Me₂SiC_l2(in DCM)─1.5 mol/Lphenol(in DCM),instead of 50%TFA(in DCM),was used as the reagent for removing N-Boc group.Trifluoromethane sulfonic acid(TFMSA)was the cleaving reagent.The yield was reasonable(60～80%).All peptides were tested for LH releasing activity in vitro.The bioassay data from the concentra-tion 0.05 mmol/L of each peptide indicated that (1) the synthetic hF-GRP and its amide(at C-ter-minal)analog possessed almost the same LH releasing activity;(2) the substitution of phe for Asn¹⁴ markedly increased the activity;(3)in truncated sequence(Thr³-phe¹³)of hF-GRP,the substitutionof Tyr for Thr³ gave rise to an inhibiting activity for LH release;(4 )other analogs did not shownotable activitv on LH release.