Glutathione plays a key role in the liver in detoxification reactions and in regulating the thiol-disulfide status of the cell. Glutathione synthesis is regulated mainly by the availability of precursor cysteine and the concentration of glutathione itself which feeds back to regulate its own synthesis. Degradation of hepatic glutathione is principally regulated by the efflux of reduced and oxidized glutathione into both sinusoidal plasma and bile. In addition, glutathione may be consumed in conjugation reactions. Under conditions of oxidative stress, the liver exports oxidized glutathione into bile in a concentrative fashion, whereas under basal conditions, mainly reduced glutathione is exported into bile and blood. The mechanism of export of reduced glutathione into bile and sinusoidal blood is poorly understood.