The new hypocalcaemic peptides of the formula 1234567891011 H-Cys-Gly-Asn-Leu-Ser-Thr-Cys-X-Leu-Gly-Thr- 1213141516171819202122 Tyr-Thr-Gln-Asp-Phe-Asn-Lys-Phe-His-Thr-Phe- 23242526272829303132 Pro-Gln-Thr-Ala-Ile-Gly-Val-Gly-Ala-Pro-NH2, wherein X represents the L-methionine, L-valine, L-norvaline, L-leucine, L-isoleucine, L-norleucine or L- alpha -aminobutyric acid radical, above all the L-methionine or L-valine radical, and wherein L-alanine26 is replaced by L-asparagine and/or L-isoleucine27 is replaced by L-threonine, and wherein optionally one or more of the aminoacids in positions 11, 12, 16, 19, 22 and 24 is or are replaced by another aminoacid, namely L-threonine11 by L-lysine, L-tyrosine12 by L-leucine, L-phenylalanine16 by L-leucine, L-phenylalanine19 by L-leucine, L-phenylalanine22 by L-tyrosine and L-glutamine24 by L-arginine.
Hypocalcaemically active peptides related to human calcitonin