Abstract: Novel cyclic analogues of callidine have the following general formula: ##STR1## wherein Pro is moiety of L-proline, Gly--that of glycine, Phe--phenylalanine, Arg--L-argenine; R is a residue of .alpha.- or .omega.-aminoacid or peptide; R.sub.1 is a residue of .alpha.- or .omega.- amino-acid; R.sub.2 is L-serine or glycine, the carbonyl group of arginine being connected either with R or with R.sub.1 by means of a covalent peptide bond using the .omega.-amino group of the aminoacid located in the 1 or 2 position of the calladine sequence. The novel compounds according to the present invention possess a prolonged hypotensive effect of selective character.