The effects to membrane filtration (using a pilot system with a 1.2 mum prefilter and a 0.65 mum final filter system) on the aromatic profile and phenolic quality of a Cabernet Sauvignon wine was studied. A statistically significant decrease (p < 0.05) was observed in the colour intensity and polyphenolic profile, with the exception of the HCl index which remained stable. In more than a hundred aromatic compounds measured, a significant difference (p < 0.05) was observed in only 12 of them. This difference caused by filtration was corroborated sensorially by a Triangle Test performed by an inexpert panel. The results obtained show that the probable cause of the observed differences is a membrane adsorptive phenomenon. (C) 2004 Elsevier Ltd. All rights reserved.