Lichens can produce secondary metabolites with important biological activities such as antioxidants, antibacterial, etc. Physodic acid (PA) is an important lichen secondary metabolite. The anticancer activity of PA has been shown in many tumor types other than lung cancer. The aim of this study was to investigate the effects of PA on A549 lung adenocarcinoma cells. In this study, A549 lung cancer cell line was used. MTT and colony formation assays were used to evaluate cytotoxic effects of PA at 24, 48, and 72 h; hematoxylin-eosin staining and DAPI staining were used for determining cell and nucleus morphology, respectively, and wound healing assay was used for investigating cell migration. PA was shown to be cytotoxic in 24, 48, and 72 h by increasing concentrations. IC50 concentrations at 24, 48, and 72 h were found to be 382.0, 235.4, and 175.8 mu M, respectively. PA was found to inhibit colony formation completely at non-toxic concentration. It was observed that PA disrupted cell and nuclear morphology and showed apoptotic activities by increasing concentrations. It was determined that non-toxic and higher concentrations of PA inhibited cell migration widely. In conclusion, PA was shown to have cytotoxic, apoptotic and cell migration inhibitory effects on A549 lung adenocarcinoma cell line.