Biodegradable crosslinked biopolyesters based on the fumarate ester of castor oil and methylolated cardanol were prepared using naturally available byproducts of cashew nut shell liquid (cardanol) and castor oil by the condensation of the crosslinking agent’s vinyl acetate (VA), n-vinyl pyrrolidone (VP), acryllonitrile (AN), methylacryllate (MA) and methyl methacryllate (MMA) respectively. These biodegradable polyester resin blends were subjected to antimicrobial activity under bacterial attack.