Supercritical antisolvent fractionation (SAF) was evaluated in the fractionation and concentration of a family of beneficial plant compounds called lignans from the ethanol extract of flaxseed. The amount of lignans obtained in different fractions was studied under varying pressures (10-30 MPa), CO2 flow rates (5-15 kg h(-1)) and times of treatment (60-180 min) in a three-stage fractionation column with constant temperature fixed at 313,323 and 333 K. The determination of lignan content was performed by HPLC coupled with a coulometric array detector. The effects of each individual variable as well as their interactions were investigated using a full factorial design with three factors and two levels and the optimal conditions were calculated through response surface methodology. A statistically significant increase in lignan content was obtained after the SAF process; from an average initial lignan content of 1.66 +/- 0.13 g L-1 it was possible to obtain a total lignan content ranging from 3.42 to 12.96 g L-1. We conclude that SAF is an appropriate technique for the isolation of lignans from flaxseed. (c) 2013 Elsevier B.V. All rights reserved.