Abstract Cultures of adult rabbit hepatocytes have been used to study the early toxic effects of 2 model hepatotoxins, dimethylnitrosamine and allyl alcohol. Leakage of glutamate oxaloacetate transaminase and glutamate pyruvate transaminase into the cell culture medium was a sensitive indicator of plasma membrane damage by these compounds and a dose-response relationship was observed. By contrast, γ-glutamyltranspeptidase and alkaline phosphatase were insensitive markers. The effects of dimethylnitrosamine were slower to develop. Dimethylnitrosamine also produced a dose-related inhibition of protein synthesis after 4 h, a decrease in NADPH diaphorase and an increase in non-specific esterase after 20 h. Dimethylnitrosamine, unlike allyl alcohol, caused extensive disruption of ribosome association with the endoplasmic reticulum.