A new aromatic derivative, 5-(3,4-dihydroxyphenyl)-3-methylcyclohex-2-enone (1), and three known compounds, peltigerine, solorinine, and phenyl butanoid, were isolated from the MeOH extract of the lichen Peltigera dolichorrhiza (Peltigeraceae). Their structures were determined by 1D and 2D nuclear magnetic resonance and mass spectroscopy analysis.