Phlomis lychnitis L. (Lamiaceae) is consumed as a traditional herbal tea in Spain. The antioxidant-protective effects as well as its phytoconstituents have never been established. The ability of the methanolic extract to protect cells from oxidative stress was evaluated in rat pheochromocytoma cells (PC12) using hydrogen peroxide as toxic agent. The viability of PC12 cells pre-treated with the methanolic extract of Phlomis lychnitis, determined by the MTT and LDH assays, was significantly improved at the highest dose (p < 0.01). The antioxidant activity was confirmed evaluating the capacity of the plant to scavenge ABTS, DPPH, O(2) . (-) radicals and to inhibit XO. Bioassay guided fractionation led to antioxidant compounds. Qualitative HPLC/DAD/ESI/MS analysis reported phenylpropanoids, verbascoside being the major antioxidant constituent.