Toxic organochlorines that are present in food are lipophilic and carried by chylomicrons. We have studied the clearance of an organochlorine, hexachlorobenzene, from chylomicrons. Chylomicrons were obtained from mesenteric lymph of rats that were intraduodenally given 14C-hexachlorobenzene and 3H-triolein. The labeled chylomicrons were injected intravenously into recipient rats, and the clearance of isotopes was followed. Surprisingly, the hexachlorobenzene disappeared from the plasma more rapidly than the triolein. This unexpected result raises questions about the manner in which hexachlorobenzene is delivered to tissues. The tissue distribution of the hexachlorobenzene is consistent with its rapid uptake.