An analysis of the application of supercritical carbon dioxide in the extraction of bioactive compounds from Helianthus annuus L. (sunflower) has been carried out. The influence of different variables, including pre-treatment of the sample, temperature, pressure and modifiers, was investigated. The samples were either dried or not dried and the extraction conditions were as follows: 35-50 degrees C, 100-500 bar, and addition of 5% of methanol, water or dimethyl sulphoxide (DMSO) as a modifier. The best extraction yields were achieved on a dried sample at a temperature of 50 degrees C and a pressure of 500 bar using a 5% water as a modifier. The bioactivities of the extracts obtained under the different conditions were compared. The best activity profiles were obtained for the non-dried samples extracted at 50 degrees C and 500 bar with supercritical carbon dioxide. (c) 2006 Elsevier B.V. All rights reserved.