This study tries to elucidate the anti-proliferative and apoptotic effects of methanolic lichen extracts from Cladonia rangiformis and Cladonia convolute in MCF-7 human breast cancer cells. Lichen extracts (0-2 mg/ml) were added to MCF-7 cells for 24 h. Cell viability was tested using 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. Cell proliferation was observed using bromodeoxyuridine (BrdU) labelling and proliferating cell nuclear antigen (PCNA) by immunocytochemistry. The TUNEL method was used for cell death detection. The effective dose (ED50) values of methanolic extracts from C. rangiformis and C. convolute were found to be 0.905 and 0.977 mg/ml, respectively. Treatment with C. rangiformis methanolic extract (0.2-0.8 mg/ml) dose-dependently inhibited proliferation of MCF-7 cells as detected by BrdU incorporation. The inhibition was started in 0.2 mg/ml concentration of C. convoluta methanolic extract. The percent of PCNA immunopositive cells showed a decrease in MCF-7 cells treated with two lichen extracts compared to control MCF-7. Both methanolic extracts showed a significant increase in percentage of apoptosis-positive cells. These results indicate that methanolic lichen extracts from C. rangiformis and C. convolute inhibited proliferation of MCF-7 cells and caused apoptosis in MCF-7 cells. The lichens may be novel natural agents for treating breast cancer disease.