Parmotrema tinctorum was extracted successively with n-hexane, chloroform, acetone and methanol using a soxhlet process. The cytotoxic activity of the four lichen extracts was evaluated on two human cancer cell lines (MCF7 and NCI-H460) by sulforhodamine B (SRB) assay. The results showed that the chloroform extract exhibited the highest activity with IC₅₀ 32.8 µg/mL for MCF7 and 60.7 µg/mL for NCI-H460. The phytochemical study on this extract led to the isolation of five phenolic compounds including orsellinic acid 1, methyl orsellinate 2, methyl β-orsellinate 3, lecanorol 4 and atranorin 5. Their structures were elucidated by ESI-HRMS, NMR analysis and compared with literature data.