Disclosed are x-ray contrast compositions for oral or retrograde examination of the GI tract comprising a polymeric material capable of forming a coating on the GI tract, said polymeric material having atoms containing polarizable electrons thereon, in combination with a divalent cation; and an x-ray contrast producing agent of the formula

wherein
Z = H, halo, C 1 -C 20 alkyl, cycloalkyl, lower alkoxy, cyano, where the alkyl and cycloalkyl groups can be substituted with halogen or halo-lower-alkyl groups; R = C 1 -C 25 alkyl, cycloalkyl, or halo-lower-alkyl, optionally substituted with halo, fluoro-lower-alkyl, aryl, lower-alkoxy, hydroxy, carboxy, lower-alkoxy carbonyl or lower-alkoxy-carbonyloxy, (CR 1 R 2 ) p - (CR 3 = CR 4 ) mQ , or (CR 1 R 2 )p - C ≡ C - Q; Ri, R 2 , R 3 and R 4 are independently lower-alkyl, optionally substituted with halo; x is 1-3 y is 1-4; n is 1-5; m is 1-15; p is 1-10; and Q is H, lower-alkyl, lower-alkenyl, lower-alkynyl, lower-alkylene, aryl, or aryl-lower alkyl; in a pharmaceutically acceptable carrier and a method of its use in diagnostic radiology of the GI tract.