The water soluble antioxidant properties of Cichorium intybus var. Silvestre, whose production zone is around Chioggia, Italy, were investigated. Vegetable juices were obtained by centrifugation, and (1) filtration at 2 degrees C; (2) filtration at 25 degrees C, and stored for 3 h; (3) boiled for 30 min at 102 degrees C, and then analysed. The antioxidant properties were evaluated in vitro as antioxidant activity (AA) (model system beta-carotene-linoleic acid) and ex vivo as protective activity (PA) against rat liver cell microsome lipid peroxidation measured as 2-thiobarbituric acid-reactive substances (TBA-RS) generated by peroxide degradation. All the vegetable juices showed high but very variable AA (> 83%) and PA (> 64%). After dialysis and analysis of fractions it was shown that the vegetable contained both biological antioxidant and prooxidant compounds. The prooxidants had MW < 3000, conversely the very active antioxidants (PA = 100%) had MW > 15,000. Electrophoretic analysis revealed that the most active fraction was a complex mixture of brown components at MW > 300,000.