Abstract:In the continuing search for exploitation and utilization of lichens, we have isolated 12 compounds from 4 species of medicinal lichens used in the North-western China. Their structures were deduced from spectral and chemical evidence, and the constituents are as follows: 1. Lethariella zahlbruckneri (DR.)Krog, atranorin (1), ethyl haematommate (10), methyl β-orcinolcarboxylate (8), (–)-placodiolic acid (4). 2. Lethariella cladonioids (Nyl.) Krog. Syn., methyl β-orcinolcarboxylate (8), haematommic acid (9), atranorin (1), norstictic acid (2), 8‘-O-ethylnorstictic acid (3)- 3. Cladonia stellaris (Opiz.) Pouzar & Vezda, (+)-usnic acid (5), perlatolic acid (6), atranorin (1), 2, 4-dihydroxy-6-n-pentylbenzoic acid (12), 2-hydroxy-4-meth- yoxy-6-n-pentylbenzoic acid (11). 4. Dermatocarpon miniatum (L.) Mann., D-volemitol. A colour substance canarionic acid reported previously occuring in the genus Lethariella was proved to be identical with (–)-placodiolic acid.