A series of amino acid and peptide derivatives of estradiol have been synthesized by coupling 17 beta-aminoestra-1,3,5(10)-trien-3-ol, 17-hydrazonoestra-1,3,5(10)-trien-3-ol with amino acids or peptides, using tetrahydrothiazole-2-thione, N-hydroxy-1,4-epoxycyclohex-5-ene-2,3-dicarbonylimide, benzotriazolyloxy-tris(dimethylamino)phosphonium hexafluorophosphate, and p-nitrophenol as reagents. N-protected peptidyl steroids were deprotected by traditional methods. The relative binding affinities of the deprotected derivatives to the estrogen receptor were determined by competitive radioligand binding assay.