Abstract: Novel radioiodinated analogues of naturally-occurring cholestrol esters, arylaliphatic cholesteryl ethers, are selective for low density lipoproteins and have been shown to be successful imaging agents for adrenal glands. The arylaliphatic cholesteryl ethers have the general formula: ##STR1## where X is a radioactive isotope of iodine and n is an integer between 1 and 20. Two illustrative examples, m-iodobenzyl cholesteryl ether and 12-(m-iodophenyl) dodecyl cholesteryl ether, were radiolabeled with .sup.125 I by an isotope exchange reaction. Tissue distribution studies indicate significant accumulation of the cholesteryl ethers in the adrenal glands, and to a lesser extent in the liver. The cholesteryl ethers selectively incorporate into plasma lipoproteins as determined by polyacrylamide gel electrophoresis.