The formation of multilamellar inclusion bodies in cytoplasm is a generalized cellular response to treatment with a variety of chemical agents. The present study was conducted to determine if a correlation exists between acute lamellar body induction potency and cytotoxicity in the perfused rat liver. Livers were perfused for 3 hrs with various concentrations of erythromycin, gentamicin, sulfate, or trospectomycin sulfate, all of which are known to produce lamellar bodies in the rat in vivo. At the end of the experiments, the livers were perfusion fixed for transmission electron microscopy. Based on the bile flow rate, perfusion rate at constant pressure, and cytoplasmic enzyme release, neither gentamicin nor trospectomycin was hepatotoxic at concentrations up to 1.8 mM, whereas erythromycin was toxic at 0.1 mM. Gentamicin caused no ultrastructural changes compared to controls, but trospectomycin caused the dose-dependent formation of lamellar bodies in hepatocytes without other cytoplasmic alterations. Erythromycin caused cellular degeneration accompanied by an increase in the number of secondary lysosomes, but these lacked lamellated inclusions. It is concluded that hepatic lamellar bodies can be induced in acute ex vivo experiments, but that their formation does not appear to be linked with acute cytotoxicity.