AbstractIn 1974 Fanaroff & Riley divided the extended radio sources into two classes, on the basis of their radio morphology and power. For several years we have been collecting basic parameters for extragalactic jets detected in the X-rays, looking for an extension of the classification criterion, based on their radio and X-rays properties. The fact that different processes have been proposed to explain their X-ray radiation, (synchrotron vs inverse Compton emission) suggests the possibility of a new classification scheme. However, comparing the radio-to-X-ray properties of the extragalactic jets, several aspects on their nature became unexpectedly unclear.