Hepatic artery ligation (HAL) is a model for inducing a vascular attack on liver tumours which causes a reduction in tumour growth. To determine in an experimental rat liver adenocarcinoma the duration and magnitude of changes in adenonucleotide concentration and energy charge (EC) after HAL, analyses of energy-rich nucleotides were performed at 1, 2, 24 and 168 hours after HAL or a SHAM procedure. There was a significant decrease of the ATP content and energy charge in the tumour one hour after HAL. Two hours after HAL this difference had decreased and with longer observation it was not detectable. Twenty-four hours of starvation did not significantly alter the effects of HAL on the tumour. HAL gives rise to a transient energy depletion of the tumour which is not completely compensated for by glycolysis after 1 hour, but is restored after 2 hours.