The present work evaluated the antioxidant capacity of six plants commonly used in traditional Moroccan medicine. The antioxidant capacity was estimated by DPPH test, ferrous ion chelating activity and ABTS test. As results, the highest antioxidant activities were found in Mentha suaveolens, Salvia officinalis and Mentha viridis. Different species showed significant differences in their total phenolic content (TPC). The highest level of phenolics was found in Salvia officinalis and the lowest in Pelargonium roseum. Linear correlation was found between TPC, especially the non-flavonoid content (NFC) and the antioxidant activity. Qualitative and quantitative analyzes of major phenolics by reverse-phase high-performance liquid chromatography (RP-HPLC) were also performed. On the basis of the obtained results, these studied medicinal herbs were found to serve as a potential source of natural antioxidants due to their richness in phenolic compounds and marked antioxidant activity.