The toxicity, uptake, tissue distribution, elimination, and covalent binding of [1-14C]allylnitrile (ALN) in male Sprague-Dawley rats were investigated. Following an oral administration of 57.5 mg/kg body weight (0.5 LD50, 23.4 mu Ci/kg, body weight), the rats exhibited several signs of toxicity, including ataxia, convulsions, mild diarrhea, salivation, lacrimation, and bladder urine retention. The treated animals excreted 41% of the radioactivity in the urine, 6% in the feces, and 34% in the expired air in 10 days. Hydrogen cyanide was not detectable in the expired air. Red blood cells retained significant amount of radioactivity for more than 5 days after treatment. ALN was extensively absorbed through the gastrointestinal tract and distributed in all the tissues of the rats. The major concentrations of the radioactivity were found in bone, kidney, blood, and the gastrointestinal tract. The subcellular fractions of the liver, kidney, heart, lung, and brain showed substantial accumulation of radioactivity from ALN up to 48 hr following dosing. Among the chemical fractions of the liver, the proteins exhibited much higher retention of radioactivity from ALN than the nucleic acid and phospholipid fractions, with a peak at 1 hr. This study indicates that ALN is rapidly absorbed and distributed in the rat and the major route of excretion is urinary followed by the expired air.