We immunohistologically studied the hepatic tissue sections in cases with the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome; n = 2) and acute fatty liver of pregnancy (AFLP; n = 2) compared to necropsy controls. Unlike in the AFLP cases, a marked infiltration of neutro-phils in liver tissues was found in both cases of the HELLP syndrome. Immunostaining with the antihuman (polyclonal) TNF-α, IL-lβ, IL-8 and antihuman neutrophil elastase (monoclonal antibody) was performed in paraffinembedded hepatic tissue sections. Liver tissues in HELLP syndrome patients were stained strongly with TNF-α and neutrophil elastase antibody. The strongest staining pattern was observed in the eclamptic case, whereas in the AFLP cases, as in the necropsy controls, a very weak staining for anti-TNF-α and elastase antibody was found. The liver sections of the HELLP syndrome cases were moderately stained with polyclonal IL-lβ and IL-8 antibodies whereas AFLP and controls had a very faint staining. Significant correlations were found between the numbers of necrotic hepatocytes and elastase dots in the same microscopic fields (randomly selected) of liver sections from two cases of HELLP syndrome (r2 = 0.63; p < 0.0001), which might suggest a neutrophilmediated tissue damage in such a disease. This study suggests that a cytokine-and neutrophil-mediated liver injury occurs in the HELLP syndrome but not in