If your pizza boxes are not heavily contaminated with grease, they can be recycled. If grease has soaked the cardboard, we request this part of the box be ripped off and the rest may be recycled. Grease from pizza boxes cause problems during the pulping process used to recycle paper fibers. Specifically, oil from the grease is very difficult to remove and inhibits the production of high quality paper products. As long as the cardboard isn't soaked with grease, please recycle this valuable material!