In this study, the phytochemical composition, total phenolic contents (TPC), total flavonoids contents (TFC) and antioxidant activity of crude fractions from aerial parts of Cleome amblyocarpa and C. ramosissima growing in the Kingdom of Saudi Arabia were investigated. The antioxidant activity of all extracts tested was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical, 2, 2'–Azino–bis (3-ethylbenzoline -6- sulfonic acid) diammonium salt (ABTS·+) free radical, Metal chelating activity (MCA), and superoxide radical anion ( 2) scavenging assays. Considerable amounts of TPC and TFC were measured in the extract fractions from the two Cleome species. The butanol extract from each species yielded the greatest antioxidant activity. In addition Phytochemical screening extracts of the above plants revealed the presence of tannins, alkaloids, terpenes, saponins, flavonoids, anthraquinone and glycosides.