This monograph summarizes the recent literature on macrocyclic polyesters. Achievements in the synthesis of crown ether derivatives and their fields of application are presented. Methods for introducing functional groups into benzene rings of dibenzo-18-crown-6 are described. A new method of selective alkylation of dinitrodibenzo-18-crown-6 is shown. The extraction, transport, microbiological and complexing properties of new derivatives of dibenzo-18-crown-6 are presented