The toxicity of palmitoylpentachlorophenol (PPCP), a lipid conjugate of pentachlorophenol (87865) that has been found in human fat, was investigated in the rat. Male Sprague-Dawley-rats were given 100mg/kg PPCP in mineral-oil by gavage, and the animals were sacrificed 4, 8, or 12 days (d) after the treatment. Liver, lung, heart, spleen , kidney, testes, thyroid, pancreas, stomach, jejunum, colon, forebrain, skeletal muscle, and adrenal glands were examined histologically in routine sections stained by hematoxylin and eosin. Sections of pancreas were also stained for fibrous and elastic tissue. No gross lesions were observed at necropsy, and there was no evidence of microgranulomas. Pancreas exhibited a focal loss of pancreatic acini with replacement by clear vacuolated cells at 4 and 8d after treatment. The presence of an acute inflammatory infiltrate in the pancreas parenchyma was noted at all times. Formation of fibrous tissue by 12d resolved the loss of acinar tissue. The vascular and inflammatory lesions and the resolving fibrous lesions were mainly focal, small, and scattered. The authors conclude that PPCP has a specific target organ toxicity for exocrine pancreas and causes morphological damage to this organ.