The present invention relates to a system for the rapid determination of the degree of hepatic steatosis (fat in the liver) via a direct measurement of the hepatic electrical impedance at one or more frequencies. The measurement is taken by means of surface or minimally invasive sensors, which can be coupled to other devices for medical use (e.g., laparoscopic probes). By means of an interpolation algorithm based on correlations between impedance and the percentage of hepatic fat in reference biopsies, the system is capable of determining the degree of hepatic steatosis in the organ measured immediately and without requiring any other kind of intervention. This permits its application to procedures such as liver transplant, allowing a rapid diagnosis of viability to be made, along with other surgical procedures and on explanted organs.