In this study, we present antioxidant and antimicrobial activity of isolated lignans freed of other bioactive compounds in comparison with dominant phenolic acids. The combinations of screw pressing, solvent extractions, acid-catalysed hydrolysis and flash chromatography were used to describe and isolate linseed phenolic compounds. Secoisolariciresinol, ferulic, p-coumaric and caffeic acids were the most abundant ones while salicylic, gentisic, dihydro-p-coumaric, phenylacetic, vanillic, p-hydroxybenzoic and β-resorcylic acids were the minor secondary metabolites. Anhydrosecoisolariciresinol (ANHSECO) and levulinic acid were an artefacts formed during exhaustive hydrolysis. The effective concentration (EC50), antiradical power (1/EC50), stoichiometry (2·EC50) values and second order rate constants k 2 were determined to classify antioxidants according to reaction kinetics as slow (p-coumaric acid derivatives), medium (ferulic acid derivatives, secoisolariciresinol and ANHSECO; k 2 ranges from 1.85 to 2.29 μmol−1 dm3 s−1) and fast (caffeic acid derivatives; k 2 = 6.91 μmol−1 dm3 s−1) ones. Rancimat method was simulating lipid peroxidation and its inhibition. Linseed lignans and phenolic acids could be classified according to protection of unsaturated triacylglycerols in the following order: p-coumaric acid < ANHSECO < methyl p-coumarate < ferulic acid < secoisolariciresinol < methyl ferulate < crude extract < caffeic acid < methyl caffeate. The mechanism and the formation of secoisolariciresinol oxidation products were discovered by mass spectrometry. The effect of crude linseed extract, ANHSECO, caffeic, ferulic and p-coumaric acid on the growth of Gram-negative bacteria, Gram-positive bacteria, yeasts and moulds was also determined.