The role of glutathione (GSH) and ornithine decarboxylase‐antizyme (ODC‐AZ) in the regulation of the chloroform‐mediated stimulation of rat hepatic ornithine decarboxy‐lase (ODC) was investigated. We have previously implicated roles for each while examining the chloroform effect on crude cytosolic enzyme preparations. In this study we examined the effect of pretreatment with diethyl maleate (DEM), a GSH‐depleting agent, on the chloroform stimulation of the two forms of the rat hepatic ODC enzyme and the sensitivity of these two forms to inhibition by the ODC‐AZ. While the pretreatment with DEM provided a greater amount of the two forms of the ODC enzyme, it also resulted in a differential stimulation of each form when compared to chloroform alone. Additionally, Peak II was 20–25% more sensitive to the same amount of ODC‐AZ then Peak I ODC activity.