1. Clinical, morphological and biochemical data, including data obtained from the application of subcellular fractionation techniques to liver biopsy specimens, are presented for two patients with the Dubin-Johnson-Sprinz (DJS) syndrome.
2. Subcellular fractionation experiments demonstrate that the lysosomes, which have strikingly reduced equilibrium densities, accumulate melanin. Morphological studies confirm the presence of pigments within lysosomes.
3. Although there are increased activities of lysosomal acid hydrolases in the liver tissue from patients with the DJS syndrome, the integrity of these organelles is essentially normal and therefore the accumulation of pigment would not be expected to initiate liver damage. The DJS syndrome is thus a benign type of secondary lysosomal storage disease.