The invention relates to new compounds, being 3-phenylpropionic acid derivatives of formula I wherein W represents COOH group or its bioisosters, or --COO--C.sub.1 C.sub.4-alkyl group; Y represents NH, N--C.sub.1 C.sub.10-alkyl, O, or S; Z represents NH, N--C.sub.1 C.sub.10-alkyl, N-aryl, N-heteroaryl, S, or O; X represents O, S, NH, N--C.sub.1 C.sub.10-alkyl, N-aryl, NSO.sub.2--C.sub.1 C.sub.10-alkyl, N--SO.sub.2-aryl, or N--SO.sub.2-heteroaryl; R.sub.1, to R.sub.6 each independently represent hydrogen atom or a substituent defined in the description; A is as defined in the description; n represents an integer from 0 to 4, inclusive; and pharmaceutically acceptable salts thereof. The compounds are the ligands of PPAR-gamma receptor and are useful as medicaments. ##STR00001##