The size-age and ontogenetic structure of the Usnea filipendula population, the life state of individuals and their infection with lichenophilic fungi were studies. It was found that the population is dominated by middle-aged generative individuals. The size of lichen thalli is smaller than it is typical for this species. There are many protovis body of the lichenophillic fungi on the lichen thalli. Changes in the morphology of thalli, usually observed during growth under conditions of air pollution, were not noted. The development of smaller thalli, the abundance of lichenophillic fungus fruiting bodies on the thalli indicates that environmental conditions are not optimal for the development of the species. Almost complete absence of individuals of the pre-generative period in the population shows that successful reproduction of the species does not occur. The current state of the lichen population is assessed and possible ways of is further development are discussed.