The present paper reviews data concerning the crystalline basement of all tectonic units in Hungary. Their lithologic content, biostratigraphic data, metamorphic features and radiometric age data are presented and critically discussed. The effects of at least two regional metamorphic cycles have been definitely recognized, Alpine and Variscan, and some polymetamorphic situations suggest the possible existence of a third, older event. The following main events are distinguished: the Alpine, the Variscan and an early Variscan or pre-Variscan stage or event. Alpine metamorphism turns out to be more widespread than previously reported. The Alpine metamorphic grade ranges from subgreenschist to greenschist facies conditions, locally reaching the lower amphibolite facies. Low to medium pressure conditions have been generally ascertained for it, with local exceptions of high and transitional medium to high pressure conditions. The Variscan metamorphism has been detected in the majority of the pre-Permian rock sequences in Hungary. Its metamorphic grade covers the whole temperature field of metamorphism, up to anatectic conditions. The pressure conditions in the monometamorphic Variscan low grade metapelites turn out to be low, related to a thermal gradient close to 40 °C/km. A pre-Alpine polymetamorphic character is displayed by some Variscan amphibolite facies metapelites. The youngest mineral assemblages in them are characterized by the occurrence of andalusite in the rocks of suitable bulk composition, displaying a low-pressure character of the Variscan event, consistently with the above reported pressure estimate inferred from the greenschist facies monometamorphic metapelites. The oldest mineral assemblage is characterized by the occurrence of kyanite in rocks of suitable bulk composition, which may be either referred to an early Variscan stage or to a pre-Variscan event.