Twelve genera and species of fungi were identified from surface disinfected [0.5% Ca(OCl)2 for 4 min.] mushroom pileus tissue. Overall fungi, Rhizopus sp. (30%) and Monilia sitophila (asexual stage of Neurospora sitophila Shear et Dodge) (10%) were the most frequently recovered species. Aspergillus flavus Link ex Fries, A. fumigatus Fries., M. sitophila and Chaetomium bostrychodes Zopf were found both as internal fungi in the basidiocarps and competitors on sugarcane bagasse mushroom beds. Radial growth reduction of V. volvacea by fungal competitors depended on incubation temperature and the nature of the fungal competitor present. In vitro antagonism was tested for the Chinese straw mushroom and its internal basidiocarp mycoflora. Aspergillus niger van Tieghem caused 100% reduction of mushroom mycelial growth at 27° and 35° C, whereas A. carbonarius (Bainier) Thom caused 62.5% mushroom mycelial growth reduction at 27° C, and 38.8% at 35° C. Generally the internal mycoflora was less antagonistic at 35° C than at 27° C.