Supercritical fluid extractions (SFE) from BAL 150 asphaltenes were achieved with carbon dioxide as solvent under various experimental conditions (pressure, temperature, extraction time, and presence of cosolvent). SFE yields were between 5 and 12% of total asphaltenes. Extracts contained mainly linear alkanes (with chain lengths ranging from C-14 to C-30), various branched alkanes, and a multitude of complex branched and cyclic alkanes as shown by the GC/MS chromatograms. Many aromatic hydrocarbons, heteroaromatic compounds and their methyl derivatives, and polar compounds were also extracted. The best balance between rapid and efficient extraction was obtained for an extraction time of 60 min. Within the range of the study (40-50 degrees C), the temperature did not show a marked influence upon the extraction efficiency. Pressure and presence of cosolvent appeared to be the major parameters. Increasing pressure (from 130 to 300 bar) yielded to preferential extraction of heavy n-alkanes, more branched and cyclic alkanes, and aromatics. The comparison of extractions performed with or without cosolvent (toluene and dichloromethane) under the same conditions of time and temperature showed that heavier n-alkanes, more highly branched alkanes, and complex cyclic alkanes (biomarkers) were recovered with modifiers.