This paper reviews data on the geological evolution of Western Greece, with special emphasis on the petroleum potential of the Pre-Apulian zone (including new data) and the Ionian zone, the two most external portions of the Hellenide fold and trust belt. From the Triassic to the Late Creataceous, Western Greece constituted part of the southern passive margin of Tethys and siliceous facies are widely associated with organic-carbon rich deposits. Pelagic Late Jurassic units rich in marine organic matter constitute important hydrocarbon source rocks in the pelagic neritic Pre Apulian zone succession. Oil oil correlation with an Apulian zone oil sample (from Aquila, Italy) indicates similar geochemical characteristics. Thus, the significant volumes of oil generated by the rich and mature source rock intervals identified in the Pre Apulian zone are likewise expected to be of good quality. In the Ionian zone, four organic carbon rich intervals with hydrocarbon potential have been recorder.