Large-scale thermochemical conversion under vacuum of various common wood species yielded a series of steroids which have rarely been reported in plants. Hearing under vacuum accelerates the removal of extractives from the plant biological matrices without any significant modification. Gravity-flow column liquid chromatography on silica gel, thin-layer chromatography and high-resolution gas chromatography interfaced with a mass spectrometer were the principal methods used for the separation and quantitative analysis of the steroids. Identification was based on the NBS mass spectra library search file and comparison with the gas chromatographic retention times of the authentic compounds. Steroid distributions of softwood and hardwood species were compared. Copyright (C) 1996 Elsevier Science Ltd.