There is some controversy about which method of assessment of lipid peroxidation in isolated hepatocytes is most appropriate. The present study was undertaken primarily to compare measurement of concentrations of thiobarbituric acid (TBA) reacting substances with measurement of ethane concentrations in the gas phase of the incubation flask as indicators of lipid peroxidation. Four metal salts, FeCl2, NaVO3, CdCl2, and MnCl2, were selected as agents that interact with the lipid peroxidation process. Furthermore, reduced glutathione (GSH) concentrations and enzyme leakage were assayed to determine whether there was a consistent pattern of interaction between lipid peroxidation and change in GSH concentrations and enzyme leakage. The effects of the metal ions on the concentration of TBA reactants estimated in the whole cell suspension and on the gaseous ethane concentration were similar. However, the assessment of TBA reactants was a little more sensitive, and ethane concentrations continued to climb with incubation time rather than leveling off as observed for TBA reactants. In general, the results of both assays were in good agreement. No consistent pattern of interaction between lipid peroxidation, GSH, and enzyme leakage was discernible in the results of the present study. It is suggested that perhaps the best approach to an experimental situation where lipid peroxidation is thought to be of central importance is measurement of both parameters, TBA reactants and ethane concentrations.