Abstract:A survey for invasive alien species was carried out along the Ipoly River (Danube catchment area) at the border between Hungary and Slovakia in 2010 and 2011. Lindernia dubia was found in three locations on both sides of the river. Th e paper gives the fi rst record of the species in the Ipoly (Ipel') Catchment Area (Hungary and Slovakia), previously, the species has not been reported from the Matricum fl ora district of Hungary. Th is paper describes the newly discovered localities (status of phenology, accompanied species, ecological and hydrological conditions, etc.). It also explains the spread and possible regional origin of the species. Th e recent CEU-based distribution map is also presented.