The presence of uninhibited side effects of cancer drugs often used in cancer treatment has stimulated the search for alternative therapeutic approaches. Therefore, anticarcinogenic effects of synthetic, herbal, and fungal drugs have been investigated for the treatment of various cancer types in recent studies. Lichens, symbiotic organisms of fungi and algae, synthesize metabolites with significant biological activities. The aim of the current study was to screen the anticancer potential of usnic acid on various types of nonmalignant cell lines (Vero, L929) and cancer cell lines (CaCo2, RD, Hep2C, HepG2, Wehi). The growth inhibitory effect of usnic acid was determined by MTT assay. Since this study was also designed to explore mRNA expression profiles, this paper is the first to look into the effects of usnic acid on apoptotic gene expression. The effects of usnic acid on the gene expression patterns of the tumor suppressor gene p53, proapoptotic gene Bcl-2, and Bax were studied with qRT-PCR. There was an approximately ninefold decrease in the p53 and Bcl-2 expression for usnic acid in the Wehi cancer cell line. Consequently, it is concluded that usnic acid has tumor inhibitory properties, and if indicated by further works like animal studies and clinical trials, it may be used therapeutically in the future.