Subjects with hepatic cirrhosis develop alterations of several rhythmic behavioural and biochemical patterns. Since most cirrhotic patients combine portal hypertension and hepatic impairment, our work aims to assess the extent to which rhythmical changes can be due to hepatic insufficiency or portal hypertension. This was done using two experimental models in rats, portacaval shunt model (PC) and portal hypertension by a triple stenosing ligature of the portal vein (PH). We assess diurnal locomotor activity and determine the oxidative metabolism of the suprachiasmatic nucleus (SCN) by histochemical determination of cytochrome oxidase (COX). The results show that animals with PC have altered diurnal locomotor rhythm compared to control and PH rats (p<0.001). They also present lower COX activity in the SCN (p<0.05). We conclude that rhythmic alterations are due to hepatic insufficiency and not to portal hypertension.