The terrigenous materials of the flysch deposits of the External Hellenides of mainland Greece have been characterized by their heavy mineral assemblages, based on 194 samples. Three major source types were distinguished. (1) A metamorphic source is shown by abundant garnet accompanied by traces of staurolite and chloritoid. In the source of the Pindos and Ionian zones, blueschist complexes were incorporated within the metamorphic terrains, demonstrated by the frequent occurrence of blue amphiboles. (2) The existence of ophiolitic sources is indicated by the occurrence chrome spinel. Pyroxenes, green amphiboles and partly epidote are related to volcanic/metavolcanic complexes. High ophiolitic detritus was especially found in Mid-Cretaceous turbiditic layers supplied from internal terrains. (3) Granitoid and gneiss source terrains are indicated, predominantly represented by zircon, tourmaline and apatite. This type of source is characteristic for Mid-Cretaceous turbidites sampled in western parts of the Pindos zone. In the terminal flysch deposits, granitoid detritus played only a subordinate role. An extensive recycling of Pindos Flysch material into the younger Western Hellenic Flysch can be excluded. Stratigraphic trends in the heavy mineral distribution of the terminal Pindos Flysch give insights into the changing tectonic situation of the source terrains. A regional east–west trend with changing ophiolitic detritus, observed in the Parnassos-Ghiona Flysch, points to a complex feeder system.