A continuous fluidized-bed bioreactor was developed for the decolourisation of cotton bleaching effluent with a wood rotting fungus. Different initial concentrations of effluent were tested with either glucose or starch as co-substrates. With this system, 75-80% colour removal was achieved with an initial A(400) of 4.7, using a 3 day-retention time. It showed high and stable decolourisation activity in long term continuous operation.