Nielsen, Per Miller, Diederichsen, Hans, and Linde, Niels Christian: Immunofluorescent and enzymatic staining of bile canaliculi in the same sections of the liver. Am. J. Clin. Pathol. 58: 123–126, 1972. In a previous study using the immunofluorescence method, sera from some patients with chronic hepatitis were found to react with structures which, morphologically, resembled bile canaliculi.5 During the present study, sections of the liver were first incubated with ten of these sera and stained by the immunofluorescence method. The same sections were then stained by the ATPase method for the demonstration of bile canaliculi. The bile canaliculi stained by the ATPase method were identical to the structures which were stained by the preceding immunofluorescence staining. Consequently, it seems to be histologically verified that sera from some patients with chronic hepatitis react with bile canaliculi.