The establishment of the operational conditions for the continuous treatment process of the metal complex dye Grey Lanaset G (150 mg l(-1)), in a fluidised bed bioreactor using air pulses with retained pellets of the white rot fungus Trametes versicolor has been carried out. Although the bioreactor operated under non-growth conditions, the fungus activity related to laccase production was maintained. The glucose consumption rate used to maintain the fungus was evaluated in 0.31 +/- 0.03 g glucose d(-1) DCW-1. The effect of the hydraulic retention time (HRT) on the decolourisation yield was also studied. Decolourisation was highly efficient (> 80%) for the different HRTs ranging from 18 to 120 h, and the dye removal rates ranged from 6.73 to 1.16 mg l(-1) h(-1). No direct relationship between decolourisation and extracellular enzyme activity was found, and high enzyme activities were not necessary to obtain high decolourisation percentages. The treated effluent fulfils the environmental quality standards in relation to colour, so it could be discharged into a municipal wastewater treatment plant if necessary. (c) 2006 Elsevier B.V. All rights reserved.