Tritium labelled arachidonic acid amides with dopamine, serotonin, vanillylamine and the ethyleneglycol ester moieties with high specific activity (120 Ci/ mmol) and yield (70-90%) were prepared from tritiated arachidonic acid by condensation with the corresponding amines and alcohol via mixed anhydrides or acyl fluorides. The labelled compounds were used for studying their uptake by mouse spleen lymphocytes. From the data obtained it was suggested that arachidonic acid amides permeate the membrane by means of passive diffusion, while transmembrane transport of arachidonoylethyleneglycol seems to be driven by the concentration gradient, maintained by hydrolytic enzymes. The compounds synthesized by the reported methods can also be used in receptor binding studies and in the oxidative metabolism of fatty acids amides and esters. Copyright © 2002 John Wiley & Sons, Ltd.