1. Perfused rat livers were subjected to an acid perfusate and varying degrees of ischaemia in an attempt to simulate the conditions of strenuous exercise or shock.
2. Lactate uptake and glucose output from the liver decreased during moderate ischaemia alone and more so when, in addition, the perfusate was made acidic.
3. Hepatic ATP and ADP content increased in the presence of an acid perfusate.
4. It is concluded that both ischaemia and acidosis may contribute to the diminished hepatic uptake of lactic acid in strenuous exercise and shock.