The ethanol extracts of 30 mushroom species from the order Polyporales were tested for their free radical scavenging activities by means of the DPPH free-radical scavenging and hydrogen peroxide-induced luminol chemiluminescence assays. In the DPPH radical scavenging test, 7 species gave EC50 values of less than 1 mg/mL. The highest activity was exhibited by Fomitopsis pinicola (0.09 mg/mL). However, in the hydrogen peroxide-induced luminol chemiluminescence assay, only 4 species had EC50 values of less than 1 mg/mL, with the highest activity being exhibited also by F. pinicola (0.26 mg/mL). When compared with known antioxidants, all the mushroom extracts exhibited relatively low activity in both assays. The free radical scavenging results appeared not to be correlated with the total phenol contents of the extracts.