Irpex lacteus decolourised the textile reactive dyes Reactive Blue 19 (RBBR) and Reactive Black 5. Less than 10% RBBR remained following 2 days of cultivation with the fungus whereas Reactive Black 5 was decolourised slower, requiring 10 days for about 90% decolourisation. No lignin peroxidase activity was detected in the extracellular medium of L lacteus. Low levels of Mn peroxidase and laccase activity were detected but only after most of the decolourisation had taken place. Addition of dyes to grown cultures containing these enzymes did not enhance the decolourisation rate. It is suggested that enzymic systems or processes, other than the lignin modifying enzymes, may be responsible for dye decolourisation. (C) 2003 Published by Elsevier Ltd.