The fate of radiotocopherol was studied in plasma and tissues of sheep at various intervals after injection of single intravenous doses of 3H-labelled D-&-tocopherol. Plasma samples were taken at regular intervals after dosing and selected tissues were taken from all sheep after slaughter and assayed for radioactivity and D-&-tocopherol. Sheep were killed in groups of five at 24,72, 96, 272 and 432 h postdosing. Plasma profiles were characterized as a sum of three exponential terms. A principal component analysis of tissue concentrations was carried ont to identify tissues with parallel profiles of log (disintegrations/min per pg) over time. Five groups of tissues with distinct uptake and elimination processes were identified. The D-&-tocopherol in the liver and heart appeared to be consistent with the post-distributive kinetics of a highly perfused shallow compartment, while lung kinetics appeared to reflect a non-linear kinetic process. The third group, which included the spleen, neck brachiocephalicus muscle and pancreas, had depletion rates parallel to those of plasma for 24-272 h, but slower decreases than plasma over 272-432 h. Hip gluteus muscle and kidney comprised a fourth group, with depletion parallel to plasma rates for 24-96 h but progressively slower than plasma decreases over 96-272 h. Adrenal kinetics resembled the fourth group, but had a more rapid decrease in specific activities over 24-72 h.