註釋 Novel heterocyclic acyldipeptides of formula (I) wherein Z represents an oxygen or sulphur atom or a-CH2-group; R1 represents hydrogen, a stright or branched chain 1-4C alkyl, cycloalkyl, cycloalkyl, trifluoromethyl or benzyl group; R2 represents hydrogen, a straight or branched chain 1-4C alkyl, cycloalkyl, dialkylaminoalkyl, acylaminoalkyl or benzyl group; R3 presents hydrogen, a straight or branched chain 1-12C alkyl or trifluoromethyl group; R4 and R5, which are identical or different, represent an OR6 or NHR6 group, wherein R6 is hydrogen, a stright or branched chain 1-18C alkyl or benzyl group; Y represents a CH2-, =CH- or =N-group; a REPRESENTS A -(CH2)2-group when Y is CH2-, the two rings being trans-condensed, or a (a) od (b) group, wherein R7 represents H, F, Br, Cl, a stright or branched chain 1-4C alkyl, 1-4C alkoxy, trifluormethyl, nitro, amino, alkylamino ot dialkymino group, when Y is =CH-or =N-; are prepared by reacting the corresponding heterocyclic carboxilic acid with the corresponding dipeptides using common regents for theformation of the peptide bond. The heterocyclicacyldipeptides of formula (I) and their pharmaceutically acceptable salts are usel as active compounds in medicaments having immunostimulatory and antitumor activity. 