A rat colony with mucopolysaccharidosis VI was established and the clinical, pathological, and biochemical features were characterized. Affected rats had facial dysmorphia, dysostosis multiplex, and increased urinary excretion of glucosaminoglycans (GAGs). Ultrastructural studies revealed storage of GAGs throughout the reticuloendothelial cells, cartilage, and other connective tissues, but no deposition was observed in the nervous system. Biochemical analyses demonstrated that the excreted GAG was dermatan sulfate and the activity of hepatic arylsulfatase B was < 5% of the normal mean value. Pedigree analysis showed that the phenotype was inherited as an autosomal recessive single trait. The availability of a rat model of human mucopolysaccharidosis VI should permit the development and evaluation of various strategies to treat the human disease.