The different type of liver insufficiencies have their own specific behaviour. This specificity may be called biological specificity. In a pathological condition of the liver, the biological specificity shows that it is not necessary to diagnose the disease and the patient only, it is also necessary to valorise the biological specificities that are in play. This idea of biological specificity, seems in the case of hepatic insufficiency and in other troubles, to be very fecund and gives some important possibilities of comprehension.