The formation of oxidases and peroxidases by newly isolated ectomycorrhizal fungi was examined with agar spot tests for tyrosinase, laccase, polyphenol oxidase and peroxidase as well as with the Bavendamm test. Extracellular peroxidase was released by virtually all isolates. Tyrosinase (taken as cresolase) was presumably intracellular and occurred in the majority of isolates. The strong laccase reaction was predominantly extracellular, although in some ectomycorrhizal genera the intracellular laccase seemed to dominate. Polyphenol oxidase, as the catecholase/monophenol monooxygenase complex, was found in all isolates although its detection was complicated in the presence of laccase. Lactarius and Russula and the possibly more saprotrophic Morchella showed the most intense enzyme reactions. A comparison with wood and litter decaying fungi indicated that at least some species of several ectomycorrhizal genera possess extracellular oxidative enzymes that are normally characteristic of white rot fungi. It is concluded that mycorrhizal fungi grown asymbiotically can release extracellular enzymes capable of oxidizing a wide range of aromatic compounds.