Coix lacryma-jobi L., about 20 days old and grown on watercultures, were fed with14C-ring-labelled simazine. After freeze drying, the plant tissue was extracted with chloroform and 80% ethanol. The ethanol extractable activities were fractionated on a cation exchange column. The radioactive metabolites seem to be identical with 2-hydroxy-4, 6-diethylamino-s-triazine (hydroxysimazine), 2-hydroxy-4, 6-diamino-s-triazine (ammelin) and 2-hydroxy-4-ethylamino-6-amino-s-triazine.