The excretion, blood levels, and tissue distribution of [3H]vindesine have been studied in the rat. After an i.v. administration of 500 µg/kg, [3H]vindesine was found to be distributed very rapidly to tissues. After the distribution phase, blood levels declined with a half-life near 10 hr. Excretion was mainly via the bile, and [3H]vindesine and its metabolites in bile were poorly reabsorbed in the gastrointestinal tract. Levels were relatively high in most tissues studied but appeared to be efficiently cleared from all tissues except thymus and testes. Uptake into peripheral nerves was considerably higher than into the central nervous system.