A combined HPLC-UV/PAD and HPLC-ESI/MS method allowing the fast detection and identification/structural characterisation of lignans of different structural subclasses is described. Twenty-four lignans of different skeletal types were analysed and the combined information derived from their UV and ESI/MS spectra led to the identification of group characteristics that can be used to establish the structure of unknown lignans in plant samples. This method was successfully applied to the identification of lignans in crude extracts of Linum usitatissimum L. and L. bienne Mill.