Rats fed diets with a low (0.3% of total energy) or normal (3%) essential fatty acid (EFA) content were injected intravenously with a single dose of 14C-labelled α-linolenic, arachidonic or oleic acid and the distribution of radioactivity in the tissues was compared 5 min, 1 h and 18 h after the application using whole-body autoradiography. The highest levels of labelling with all fatty acids were observed in the liver, brown fat and adrenal cortex. Specific for arachidonic acid was a high and consistent concentration of radioactivity in the myocardium at all times and for oleic acid in the white fat after 18 h. The tissue uptake of arachidonic acid was similar in both dietary groups, whereas a higher accumulation of α-linolenic was seen in most of the tissues in the low EFA group after 18 h compared to the normal EFA group. The uptake of oleic acid was higher in some tissues in the low EFA than in the normal EFA group after 1 h, but after 18 h these differences had disappeared almost completel