The purpose of this research was to bring new data regarding the phenolic composition and the antioxidant activity of L. barbarum L. and L. chinense Mill. leaves. The determination of the main polyphenolic compounds was performed using a HPLC-UV-MS method. The dominant compound found for both species was rutin, with its highest amount registered in L. chinense (24141.90±21.3 μ/g plant material) leaves. Among the flavonoidic aglycones, quercetin was found in both samples, being quantified in a higher amount in L. chinense. In the antioxidant assays, both extracts exhibited important antioxidant activities, as witnessed by the three methods, both correlated with their total polyphenolic content.