Rats were treated orally with formetanate-14C acaricide and the urine, feces, and selected tissues were analyzed to determine the fate of the compound. Formetanate was rapidly absorbed, metabolized, and excreted; 80% of the dose was eliminated in the urine and 6% in the feces by 24 hr after treatment. Selected tissues contained a total of 1.5% of the administered dose at 72 hr posttreatment. The major metabolic pathway for the acaricide in reaction sequence was: formetanate, m-formarninophenyl-N-methylcarbamate, m-formaminophenol, m-aminophenol, m-acetamidophenol, and glucuronide and ethereal sulfate synthesis from m.acetamidophenol. Formetanate and 2 metabolites containing the carbamate ester grouping intact inhibited cholinesterase in vitro at high concentrations.