Abstract: Biodegradable tennis balls are described. A biodegradable tennis ball includes a core forming a hollow interior chamber, the core made of a blend of a rubber based material, a first petroleum based material, and a first biodegradable additive. The biodegradable tennis ball also includes a felt layer overlaying a surface of the core, the felt layer made of a second blend of a second petroleum based material and a second biodegradable additive. In some cases, the biodegradable tennis ball may include an adhesive layer adhering the felt layer to the core. In some cases, the felt layer may further include wool.