This invention relates to methods of x-ray diagnostic imaging the blood pool and/or lymph system of a mammal comprising administering a contrast effective amount of a particulate iodinated aroyloxy ester contrast agent having the structure: ##STR1## wherein n is an integer from 3 to 20; R.sup.1 is H, alkyl, fluoroalkyl, cycloalkyl, aryl, aralkyl, alkoxyalkyl or acetamidoalkyl;R.sup.2, R.sup.3 and R.sup.4 are independently H, alkyl, fluoroalkyl, alkoxy, aryloxy, halogen, hydroxy, acylamino, acetamidoalkyl, --COO-alkyl, --COO-aryl, --COO-aralkyl, cyano, sulfonyl, carboxamido or sulfonamido;R.sup.5 is H, alkyl, fluoroalkyl, halogen, hydroxy, acylamino, acetamidoalkyl, cyano, sulfonyl, carboxamido or sulfonamido;R.sup.6 and R.sup.7 are independently alkyl, cycloalkyl, aryl or aralkyl; andR.sup.8 and R.sup.9 are independently H or --COR.sup.6.This invention further relates to novel iodinated aroyloxy ester contrast agents having the above structure wherein n is an integer from 5 to 20, to x-ray contrast compositions comprising such agents, and to methods of x-ray diagnostic imaging utilizing such agents.