Supercritical fluid extraction (SFE) of hydrocarbons is an attractive substitute for conventional solvent extraction. Here, an attempt is made to extend SFE to the extraction of more polar biological markers. SFE conditions, using chlorodifluoromethane (Freon-22) and carbon dioxide (CO2 as solvent, were optimized for the extraction of free carboxylic acids and sterols from a plant tissue and a recent sediment sample. Analyses of the extracts were carried out by GC-FID and GC-MS and the results were compared to those obtained by solvent extraction. The highest recoveries were obtained extracting in dynamic mode during 20 min, at 400 bar and 40°C, with a flow rate of 2 ml/min. For the sediment, extraction with CO2 is improved by addition of methanol as modifier. Our results show that supercritical fluid extraction is a valuable technique which can be applied in a routine way to the extraction of polar lipids from natural matrices