In this work, the supercritical fractionation of fatty acid ethyl esters derived from fish oil was carried out with carbon dioxide at 333 K and 14.5 MPa. The feed mixture is very complex, with over 80 different compounds detected by GC. Among them, the EicosaPentaenoic Acid (EPA) and DodecaHexaenoic Acid (DHA) ethyl esters are of major industrial interest since the consumption of these omega-3 acids has been linked to a reduced risk of cardiovascular diseases. The influence of the process parameters on the separation efficiency is an important point for an economic analysis of the overall purification process. First, the partition of the feed mixture was determined for different solvent-to-feed ratios varying between 21.8 and 143; the extract yield (i.e. the mass fraction of feed recovered as extract) has been calculated for each condition. Then, a new simplified equilibrium-stage model was developed and applied to the mixture. Supposing a constant distribution ratio, this model is able to correlate the influence of the solvent-to-feed ratio (through a calculated extract yield) on the concentration of the major 24 compounds present either in the feed or in the extract and raffinate, including components with low, medium and high distribution ratios. (C) 2016 Elsevier B.V. All rights reserved.