AbstractHepatocyte cytoplasmic inclusions in six biopsy and eight autopsy liver specimens from patients with chronic alcoholism showing unequivocal alcoholic hyalin (Mallory bodies) at the light microscopic level were defined by electron microscopy. Additionally, these structures were found to be generally identifiable in the same and other paraffin embedded liver tissue reprocessed for electron microscopy. The inclusions were ultrastructurally grouped as five nonmembrane limited and two complete or partially membrane bound admixtures of fibrillar, granular and amorphous components of variable distribution and electron density. Membrane free types included characteristic (A) interdigitating filaments, (B) closely packed filamentous and amorphous material, (C) whorl-like fibrils in parallel array, (D) loosely arranged discrete or intertwined long wavy fibrils or membranous fragments, (E) large serpiginous masses of highly electron dense amorphous material. Membrane limited forms showed (F) scattered vesicular and fibrillar or (G) uniformly particulate and fibrillar content, completely or partially surrounded by a single or double membrane respectively.The demonstrated ultrastructural diversity of hepatocyte cytoplasmic inclusions and their stability even after postmortem autolysis of paraffin processing, or both, is of significance in diagnosis as well as in potential analysis of isolated liver cell fractions.