Thirteen flavonoid compounds were isolated for the first time from the aerial parts of Erucaria hispanica (L.) Druce growing in Egypt. Their structures were established on the basis of detailed chromatographic and spectroscopic techniques (UV, 1D and 2D NMR and ESIMS). The cytotoxic activity of the methanol extract as well as some isolated compounds against four human carcinoma cell lines; breast (MCF7), liver (HEPG2), cervix (HELA) and colon (HCT116) were evaluated.