Twenty-one harrier dogs underwent a standardized liver hilus dearterialization with (7) or without (14) cholecystectomy using six sham-operated dogs as controls. Seven dogs died, only one of which was in the dearterialization and cholecystectomy group. S-OCT and s-GDH were increased at 90 minutes after dearterialization. There was no statistical difference between the groups at 90 minutes. On the first day after dearterialization, the activity of s-OCT, s-GDH, s-ALAT rose significantly (p less than 0.005). The activity of s-ASAT was, however, increased to the same extent both in the dearterialized and the sham-operated animals. A normalization of the serum enzyme activities was usually seen after one week. S-ALP increased on the first day (p less than 0.005) and still higher values were noted on the seventh day after dearterialization. Cholecystectomy did not affect any of these results except mortality. Liver oxygen consumption, in vitro was unchanged throughout the experiment. The oxygen consumption of bile duct mucosal scrapings one week after dearterialization was similar to the corresponding values in the controls. The results indicate that the dearterialization leads to a definite but mild and reversible mitochondrial and cell membrane damage. The results indicate further the need of adequate controls when the effects of dearterialization on the liver are studied.