The effects of Dermatocarpon miniatum and Parmelia saxatilis lichens on growth, total phenolic, total flavonoid contents and antioxidant potentials of in vitro medicinal plant Bacopa monnieri were investigated. B. monnieri was treated with different concentrations of methanolic and aqueous extracts of D. miniatum and P. saxatilis lichens. Total phenolic, total flavonoid contents and antioxidant activities of B. monnieri that showed the best growth with lichen application and control plant were investigated. Methanolic extract of allelopathic plants showed strongest DPPH scavenging (IC50: 27.60 mg/L) and metal chelating activities (IC50: 120.29 mg/mL) compared to the control. Also the total phenolic and flavonoid contents of allelopathic samples for both extracts had significantly (p