As part of our ongoing project of new acetylcholinesterase inhibitors from lower marine and terrestrial species, a phytochemical investigation was conducted on a foliose lichen, Lobaria pulmonaria (L.) Hoffm. (Lobariaceae), from Bosnia and Herzegovina. The study led to the isolation of a mixture of acetylated depsidones which showed a moderate activity (0.5 µg) in the acetylcholinesterase inhibition test on Thin-layer chromatography plate. Our results indicate for the first time the significance of depsidones, highly specific metabolites from lichen species, in searching for these inhibitors which still represent the best drugs currently available for the management of Alzheimer's disease.