[Show abstract][Hide abstract] ABSTRACT: In the present study, antioxidant activity of methanolic extracts of the leaves of seven Egyptian Cassia species was investigated using two methods, the phosphomolyb-date method and 1,1 diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity method.· The results revealed that C. glauca is the most potent species and that the activity of other plant species decreases in the following order: C. grandis > C. nodosa > C. fistula > C. didymobtrya > C. occidentalis > C. sophera. Defatted methanolic extract of the most active plant C. glauca was subjected to fractionation using different organic solvents such as CHCl3, EtOAc and BuOH. Antixidant activities of the fractions were investigated and the results showed that ethyl acetate fraction possessed high activity. Total phenolic and flavonoid concentrations of each plant extract were determined using the Folin-Ciocalteu reagent and aluminum chloride. Correlation between radical scavenging capacities of extracts and total phenolic concentration was observed.