The goal of this project is to provide support of Division of Translational Toxicology (DTT) hazard identification activities targeted toward the prevention of diseases or adverse effects caused by environmental exposure to chemical or physical agents. Toxicity testing is an important aspect of public health research in that it serves to identify chemicals that are hazardous to human health. Proper conduct of toxicology studies is required to ensure that the resulting data are reliable. This project involves the conduct of toxicity studies of triphenyl phosphate (TPHP)in rats, following exposure via dosed feed; exposures occur during gestation and lactation and for three months after weaning. TPHP is an aromatic organo phosphate flame retardant. Increased use is anticipated as this class is replacing other classes of flame retardants. Exposure to TPHP occurs in the general population via its presence in consumer products and in the environment. The data from this project will be used in the development of sound, scientific conclusions about the potential toxicity of TPHP and ultimately supports the mission and goals of DTT and risk assessment activities by other federal agencies. Keywords: toxicity, triphenyl phosphate, dosed feed, flame retardant