The objective of this study was to investigate the content of biologically active compounds and antioxidant activity (AOA) of full fat flaxseed flour (FFF), roasted full fat flaxseed flour (RFFF), defatted flaxseed flour (DFF) and roasted defatted flaxseed flour (RDFF) flour as well as to evaluate anticancer effect of lignans ethanolic extracts from defatted and roasted defatted flaxseed for in vitro cytotoxicity against breast and colon carcinoma cell lines. The results revealed that roasted defatted flaxseed flour samples (RDFF) contained higher values of crude protein (32.86%), ash (6.60%), crude fiber (14.03%) and total carbohydrate (42.16%) than other flaxseed flour samples. Results showed that RDFF had significantly (P<0.05) the highest amounts of total phenolic contents, total flavonoid contents, tannins content and antioxidant activity (871.15 mg GAE/100g, 199.12 mg CE/100g, 83.51 mg CE/100g and 78.99%, respectively). Meanwhile, FFF contained the lowest values (643.04 mg GAE/100g, 112.46 mg CE/100g, 60.33 mg CE/100g and 75.80%, respectively). It was observed that, ferulic acid was the predominant phenolic acid in defatted flaxseed samples. Also, Secoisolariciresinol diglucoside(SDG) is the predominant lignans precursor present in flaxseed.Furthermore, DFF and RDFF were higher in lignans values compared to that of full fat and roasted full fat flaxseed flours. Cytotoxicity effect of lignans ethanolic extracts from defatted and roasted defatted flaxseed on colon carcinoma cell line (HCT) and breast carcinoma cell line (MCF-7) increased as the extract concentration increased. RDFF had strong anticancer activity toward two tested cell lines (MCF-7 and HCT) with the half maximal inhibitory concentration (IC₅₀) values (29.0 and 31.4 µg/ml, respectively). While, defatted flaxseed revealed anticancer activity against (HCT) cell line (with value 48.2 µg/ml of IC₅₀) compared to (MCF-7) cell line at concentration under investigation (12.5, 25, 50 and 100 µg/ml of lignans extract).