The lichens growing on Quercus were studied at 92 plots placed in 62 selected localities spread throughout Sardinia (Italy). Information on the distribution and ecology (e.g. phorophyte preference, altitudinal limits, nitrophily, photophily, hygrophily, commoness-rarity status) of each taxon is given; in many cases such information was poorly known, especially for the Mediterranean region. Finally, problems related to the conservation of lichens are treated.