The basidiomycete fungus Phellinus noxius is well known as a forest recycling agent, however, it has been responsible for a significant number of tree deaths in public parks and gardens in south east Queensland. Management of the pathogen in public places must rely on environmentally-friendly approaches such as biocontrol and biofungicides. Numerous Trichoderma spp. have been initially screened in vitro for their antagonism towards P. noxius strains isolated from dead Ficus sp., Caesalpinia ferrea (leopard tree) and Araucaria cunninghamii (hoop pine) trees. Trichoderma spp. showed various levels of antagonism against tested P. noxious isolates. Of the nine tested Trichoderma isolates, five produced volatile and non-volatile metabolites that suppressed growth of P. noxius by up to 46% and 90%, respectively. Data collected from dual culture assays also indicated that the five Trichoderma isolates adversely affected the viability of P. noxius, with recovery of one isolate of P. noxius completely inhibited. The other four Trichoderma isolates were only observed as strong growth competitors. Mycoparasitism of the Trichoderma spp. towards P. noxius was only occasionally observed at the Trichoderma-Phellinus interaction zones implying that this is probably not an important mode of action of the Trichoderma against the P. noxius. Further pot and field site trials are warranted for those Trichoderma showing promising antagonistic effects against P. noxius.