No more than 200 epiphytic lichen species of the total 423 known in Slovakia are assumed to occur at present. A small group of acidophilous and nitrophilous species is spreading. Probably only 15-20 per cent of the local epiphytic flora is prospering, and the majority is more or less endangered. The decrease or increase of some species is shown here on 9 maps. In the near future the invasion of acidophilous lichens will probably decline and less sensitive epiphytes may return to their former abundance as air pollution decreases. Nevertheless many critically endangered species very probably will go extinct