Phoxim and fenvalerate are pesticides that are most widely used as commercial formulae in China. Fenvalerate belongs to the pyrethroid compounds [Benzeneacetic acid, 4-chloro-α-(1-methylethyl)-, cyano (3-phenoxyphenyl) methyl ester. CAS registry number: 51630-58-1], while phoxim is an organic phosphate (3,5- dioxa-6-aza-4-phosphaoct-6-ene-8-nitrile, 4-ethoxy-7- phenyl-, 4-sulfide. CAS registry number: 14816-18-3). The metabolism of fenvalerate has been studied in vivo1), but the metabolism and distribution of its mixture with phoxim have not been reported in literature. A recent epidemiological investigation showed that the incidence of poisoning caused by the two mixed pesticides was three times higher than that by either one alone under similar exposure conditions2). The purpose of this study was to determine the toxicokinetics of these pesticides in order to provide information for furthering the toxicity mechanism.