Hepatic metabolism in intact livers has been studied by 31P nuclear magnetic resonance (NMR) spectroscopy. 31P NMR spectroscopy of normal liver detects little ADP and much lower amounts of inorganic phosphate than are found by enzymatic or chemical analysis. Ischaemia of 30 min duration provokes a rapid fall in ATP to undetectable levels; reflow restores the ATP concentration to 70% of its former level. Intracellular pH changes are qualitatively similar. Fructose and glycerol both cause rapid falls in ATP and inorganic phosphate; these original concentrations are almost restored after 30 min in the case of fructose but not with glycerol where they remain depressed.