Laccase is usually produced via chemical induction and is also synthesized by hosts in interaction with the typical bio-control genus Trichoderma. In this study, we found that a newly isolated non-laccase-producing fungus, Gongronella sp. W5, could induce overproduction of laccase in Panus rudis. The enzyme activity, 148,200 U l(-1), was 25 times higher than the activity obtained from a chemical induction using copper/o -toluidine as inducers. A new laccase isozyme from the interaction of P. rudis and G. W5 was purified and characterized. A further test showed that some pH resistant metabolites secreted by G. W5 acted as signals to induce P. rudis laccase. Laccase is also highly expressed by Trametes sp. AH28-2 in interaction with Trichoderma sp. ZH1. However, no laccase activity was observed from the cross-over interactions of P. rudis -Trichoderma sp. ZH1 or Trametes sp. AH28-2-G. W5.