Evidence indicates that the accumulation of glutamine in the brain plays an important role in the pathogenesis and severity of the encephalopathy of acute liver failure (ALF). This study uses in vivo proton magnetic resonance spectroscopy (1H MRS) to assess brain glutamine (GLN) in five cases of acute liver failure. The findings are consistent with prior investigations and suggest that the alpha 1H of the GLN molecule can be used for noninvasive spectroscopic quantitation of brain GLN in patients with ALF.