Abstract: A sustained-release preparation which comprises a physiologically active peptide of general formula: wherein X represents an acyl group; R1, R2 and R4 each represents an aromatic cyclic group; R3 represents a D-amino acid residue or a group of the formula: wherein R3′ is a heterocyclic group; R5 represents a group of the formula —(CH2)n—R5′ wherein n is 2 or 3, and R5′ is an amino group which may optionally be substituted, an aromatic cyclic group or an O-glycosyl group; R6 represents a group of the formula —(CH2)n—R6′ wherein n is 2 or 3, and R6′ is an amino group which may optionally be substituted; R7 represents a D-amino acid residue or an azaglycyl residue; and Q represents hydrogen or a lower alkyl group, or a salt thereof and a biodegradable polymer having a terminal carboxyl group.