White Leghorn cockerels were fed commercial DDT at levels of 250, 500, and 1000 μg/day in the diet. The absorption, distribution, and metabolism of DDT in plasma, brain, liver, kidney, heart, breast muscle, intestinal tract, skin, and fat were investigated, using gas–liquid chromatography in the quantitation of the residues. To aid in assessing chlorinated hydrocarbon toxicity in wild birds, correlations between observed symptoms and the residue levels in possible target tissues were studied in conjunction with the mechanism of action of DDT. The results indicate that the sum of the residues of p,p′-DDD, o,p′-DDT, and p,p′-DDT (toxic residues) in the brain was the best parameter for diagnosing DDT poisoning in birds. Signs of DDT toxicity were observed in all birds with brain levels in excess of 35 p.p.m. The lowest level of toxic residues in the brains of dead birds was 27.7 p.p.m. The mean brain level of toxic residues in tremoring and dead birds was 54.2 p.p.m. Metabolism and the significance of the levels of DDT and metabolites detected in other tissues are discussed in relation to the physiological function and metabolic activity of the particular tissue.