This work examined the effects of low-oxygen conditions, achieved with either argon or nitrogen gas, on the viability of the wood-decay fungi Antrodia vaillantii, Coniophora puteana, Gloeophyllum trabeum, Serpula lacrymans, and Trametes versicolor cultivated on infested wood samples. The fungal cultures were exposed to low oxygen concentrations, below 20 ppm, for one to five weeks in hermetically sealed vessels or gas-impermeable double-enveloped plastic enclosures. After treatment, CO2 production of cultures was measured to determine if mycelia regenerated. In addition, the ability of hyphae to resume growth was also assessed by transferring the treated blocks to fresh nutrient agar. The effect of the anoxic conditions on the mycelia of treated blocks was expressed as either a complete absence of regrowth of the fungus or as a delay in the mycelia's recovery. Results clearly showed that argon was more effective than nitrogen gas at reducing or eliminating fungal activity. Anoxic treatment by either argon or nitrogen gas did not affect T. versicolor cultures in the time span of the experiment. G. trabeum was only slightly affected, and A. Vaillantii mycelial cultures proved to be less sensitive to anoxic treatment than those of S. lacrymans and C. puteana, which lost their viability completely after one month of treatment.