The production of laccase and manganese peroxidase (MnP) by Lentinus edodes (Shiitake) was studied on a solid medium in conjunction with the decolorisation of the dyes Poly R-478, Remazol Brilliant Blue R (RBBR) and Orange II. L. edodes mycelium was able to decolorise all three dyes. Nitrogen (N) concentration-dependence studies with three N sources (ammonium chloride, peptone and malt extract) revealed that the range 1-3 mM N was optimum for both enzyme production and dye degradation, regardless of the N source or dye used. MnP production and the decolorisation of Poly R-478 and Orange 11 were inhibited completely above 8 mM N. The enzymatic processes also exhibited a Mn concentration dependence; 20 muM Mn proved optimum for dye decolorisation. The addition of natural supplements (oak sawdust and wheat straw) greatly enhanced MnP production. Oak sawdust had a positive effect on the decolorisation of each of the dyes investigated. A medium containing 10 g/l starch, 3.5 g/l malt extract and 20 g/l oak sawdust proved optimum for the enzymatic processes investigated.