A predominant polysaccharide isolated from Ischnoderma resinosum underwent evaluation for its capacity to scavenge free radicals and its potential antioxidant properties at a cellular-oriented level. This proved that Ischnoderma resinosum polysaccharide (IRP) remarkably curtailed AAPH-induced erythrocyte hemolysis through the inhibition of the generation of ROS (p 2O2-induced HepG2 cells, there was a statistical elevation in cell survivability (p p p 2O2-induced oxidative damage in HepG2 cells. This provides a basis and theoretical reference for the development and utilization of IRP as a natural antioxidant, with emphasis on the exploitation of environmentally friendly and cost-effective antioxidants.