In native cryostat tissue sections of adult female albino rat liver the activities of succinate dehydrogenase (E. C. 1.3.99.1), glucose-6-phosphatase (E. C. 3.1.3.9) and malic enzyme (E. C. 1.1.1.40) were histochemically demonstrated and planimetrically determined. The areas of the enzymes with a maximum activity in the periportal regions, namely SDH and G-6-Pase, were respectively 34% and 41% of the whole parenchyma. Malic enzyme showed a maximum activity in the perivenous region, which consisted of about 53% of the total parenchyma. The zonal distribution of enzyme activities is related only to the terminal vessels; in the vicinity of the preterminal vessels an irregular distribution pattern was found. The results further support the assumption of the bifunctionality of liver parenchyma.