The usual characterization of musts and wines is based on chemical composition and sensory considerations. We aim to describe the grape juice using mainly dielectric parameters, as well as examining the data using statistical methods in order to find out a possible connection among these values and the variety or the area where the samples were collected from. Red wine grape juice samples were used for measuring dielectric constant and loss factor at 0.2 and 3 GHz together with the electrical conductivity. The main varieties chosen were merlot, tempranillo and cabernet sauvignon, because these are the most important types of grape used in Navarra for barrel aging wines. We observed the existence of differences among the three varieties in relation to the values of total and dipolar losses at 3 GHz, but these preliminary results are not decisive enough. More measurements are considered as necessary, (C) 2001 Elsevier Science Ltd. All rights reserved.