This work assessed the application of one- and two-stage mesophilic anaerobic systems to colour removal of sulphonated mono and diazo dyes with ethanol as electron donor. The dyes Congo Red (CR), Reactive Black 5 (RB5) and Reactive Red 2 (RR2) were selected as model compounds and tested separately in seven different periods. The one-stage system (R-1) consisted of a single up-flow anaerobic sludge blanket (UASB) reactor, whereas the two-stage system (R-2) consisted of an acidogenic UASB reactor (R-A), a settler and a methanogenic UASB reactor (R-M). For CR and RB5, no remarkable difference was observed between the colour removal performance of both anaerobic systems R-1 and R-2. The experiments with RR2 revealed that R-2 was more efficient on colour removal than R-1, showing efficiencies almost 2-fold (period VI) and 2.5-fold (period VII) higher than those found by R-1. Additionally, R-2 showed a higher stability, giving a good prospect for application to textile wastewaters. Finally, the acidogenic reactor (RA) had an important role in the overall decolourisation achieved by R-2 during the experiments with CR and RB5 (>78%), whereas for RR2, a more recalcitrant dye, RA was responsible for up to 38% of the total colour removal.