Ultrastructural examination was carried out in 13 liver biopsies from patients with alcoholic hepatitis, with special reference to the relationship between alcoholic hyaline (AH)-containing hepatocytes and inflammatory cell infiltration. In as many as one third of the cases, polymorphonuclear leucocyte (PMN) migration into the cytoplasm of AH-containing hepatocytes was noted. The migrating PMNs often had discontinuous cell membranes and their primary and secondary granules were demonstrated to be released into the liver cell cytoplasm. Finally, migrating PMNs appeared collapsed and dying. These PMNs appeared to gather around AH, presumably due to the strong chemoattractive action of AH. The hepatocytes invaded by PMNs revealed various degrees of degeneration and cell necrosis. Occasionally, some lymphocytes infiltrated into hepatocytes and had a direct contact with AH. However, the occurrence of lymphocyte migration was much less than that of PMNs. Kupffer cells were also intermingled with these PMNs and often possessed AH in degraded forms in their phagosomes or phagolysosomes. Based on these results, it is postulated that acute hepatocellular damage in patients with alcoholic hepatitis might be caused by this peculiar type of degranulation and collapse of migrating PMNs against AH-containing hepatocytes in addition to the various causes previously studied.