A preparative supercritical fluid chromatography process to obtain enriched fractions of eicosapentaenoic ethyl ester (EPA-EE) is investigated. The starting mixture, containing about 68% of EPA-EE, is fractionated by a silica adsorption column where carbon dioxide (CO2) is used as the supercritical solvent. Different types of silica gel are used and compared. Experiments are carried out first on a bench-scale apparatus and then on a pilot plant. fluted samples are collected and successively analyzed by capillary and packed column gas chromatography. Different process operating conditions are examined and discussed. In the bench scale equipment a 95% EPA-EE fraction is achieved, in the pilot plant the maximum purity is 93%. The amount of arachidonate ethyl ester is lowered. Yields higher than 40% w/w are generally obtained. Issues related to the scale-up of the process are briefly addressed. (C) 2000 Elsevier Science B.V. All rights reserved.