Vegetation changes taking place over a period of approximately 30 years in old Scots pine stands growing on dry and subdry heaths(Callunasite type andVacciniumsite type) in southern Finland were examined on 16 permanent sample plots. The coverage ofDicranum polysetumincreased on the average from 11% to 22%, and the frequency from 81% to 97%. The coverage ofPleurozium schreberidecreased from 53% to 41%, and that ofHylocomium splendensfrom 15% to 8%. The coverage of lichens, mainlyCladoniaspecies, decreased on theCallunasite types on the average from 30% to 22%, and the frequency from 91% to 78%. The coverage ofVaccinium vitis‐idaeadecreased on the average from 33% to 20%. The changes inVaccinium myrtillusandCalluna vulgariswere less, and more variable on the different types of site, than those ofVaccinium vitis‐idaea. No marked changes were found in the occurrence of grasses or herbs. The material does not give any definite answers to the question of which factors have brought about the vegetation changes. In additiontonatural succession and annual variation of some species, the effect of air pollution has also been given consideration.