Plasma levels of the lysosomal enzymes beta-glucuronidase and beta-hexosaminidase were studied for 6 weeks after permanent bile duct occlusion (19 animals) or sham operation (5 animals). The bile duct-occluded animals had a stable bilirubinemia throughout the observation period. The median level of beta-glucuronidase in controls was 0.45 U/l. In jaundiced animals the median level was 1.09 at 0.5 weeks, 1.28 at 2 weeks, and 1.58 at 6 weeks after bile duct occlusion. The median level of beta-hexosaminidase in controls was 18.5 U/l. In jaundiced animals the median level was 18.0 at 0.5 weeks, 20.8 at 2 weeks, and 53.3 at 6 weeks after operation. Compared with beta-glucuronidase, prominent elevation of the beta-hexosaminidase level appeared much later after bile duct obstruction, which might suggest a closer association with reticuloendothelial system function for the latter enzyme.