1. Gas–liquid chromatography and a radioreceptor assay were used to measure plasma γ-aminobutyric acid (GABA) in patients with liver disease and hepatic encephalopathy.
2. There was a significant correlation between the results obtained by the two methods, and compared with controls plasma GABA was elevated.
3. These findings suggest that the increased GABA binding inhibitory activity of plasma of these patients is probably due to GABA itself.