A revision of the genus Leptogium occurring in mainland Portugal is presented based on collections of 24 out of the 25 species previously reported for the Portuguese territory. Inclusion of L. resupinans is based exclusively on recent literature reporting this species from southern Portugal. Anatomical, ecological and geographical data on these species is provided, as well as an identification key. Leptogium plicatile is here recorded for the first time in Portugal. Leptogium aragonii, L. cochleatum, L. coralloideum, L. cyanescens, L. furfuraceum , L . pulvinatum and L. schraderi constitute new records for some Portuguese provinces. The presence of the following species previously reported from Portugal is considered doubtful: L. azureum, L. caesium, L. chloromelum, L. hildenbrandii, L. intermedium and L. microphylloides. Keywords: lichenized fungi , taxonomy, key, Iberian Península, Europe.