This study was conducted to evaluate the toxicity of the munitions compound 2,4,6-trinitrotoluene (TNT; CAS Reg. No. 118-96-7) in beagle dogs when administered daily for 26 weeks by capsule. Groups of six dogs per sex received TNT at doses of 0 (vehicle controls), 0.5, 2, 8, or 32 mg/kg/day. Toxicologic endpoints included clinical signs, body weights, food consumption, clinical biochemistry, hematology, urinalyses, organ weights, and gross and tissue morphology. The major toxic effects following the oral administration of TNT to dogs included hemolytic anemia, methemoglobinemia, liver injury, splenomegaly with accompanying histologic lesions, and death. Only the highest dose given proved to be lethal. Hepatocytic cloudy swelling and hepatocytomegaly were apparent at all doses tested. Thus, a no observable effect level was not established in this investigation.