Abstract The content and composition of biologically active substances of three varieties of flaxseeds was investigated. The flaxseeds contain 33.8 %, 38.0 % and 37.1 % glyceride oil respectively. The total content of phospholipids, mainly phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine and phosphatidic acids in the oils was 0.7 %, 1.0 % and 0.8 %. The general amounts of sterols were found to be 0.3 % in all oils. β-Sitosterol predominated (more than 50.0 %), followed by campesterol and stigmasterol. In the tocopherol fraction (731 mg/kg, 768 mg/kg and 788 mg/kg respectively) γ-tocopherol predominated (61.8 -71.3 %), followed by γ-tocotrienol. Linolenic acid (46.8 %, 49.9 % and 45.0 % respectively) was the main component, followed by oleic and linoleic acids in the triacylglycerols. Higher quantities of palmitic and oleic acids were established in the phospholipids and sterol esters. LnLnLn, LnLnL and LnLnP predominated in triacylglycerols. The oxidative stability was found to be between 6.1 -6.6 h