A complex mixture of free fatty acids (1), cerevisterol (2), a sphingosine (3), and a complex mixture of diacylglycerophospholipids (4) were isolated from the fruiting body of the basidiomycete mushroom Pseudoinonotus dryadeus and subjected to spectroscopic analyses. The antioxidant activities of the whole extract of the fungus, of the isolated fractions, and of compounds 1-4 were evaluated in two in vitro model systems: 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and superoxide anion. In each systems, the extract of fungus and compound 2 showed the same free radical scavenging activity (with SC50 data of 18.27 µg/mL and 5.75 µg/mL, respectively) compared with the positive control quercetin (DPPH assay). Compounds 1-4 were isolated from P. dryadeus for the first time.