Lignin or lignin residue by-product can be produced from black liquor of pulping process or from cellulosic ethanol process. This project studied these lignin by-products as a substitute for corncob/Superbond fillers in PF glue mixes for plywood production. Two types of lignins were evaluated in the lab tests and one of them was used in the mill trial production. PF glue mixes with up to 50% corncob/Superbond substituted with lignin were produced and evaluated for plywood production. The test glue mixes were comparable to the control in viscosity, stability and bond performance. It is technically viable that lignin or lignin residue by-product be used as a substitute for corncob/Superbond fillers in the plywood industry. Caution must be taken to ensure that all particles of lignin pass a 100-mesh screen and the glue mix passes a 40-mesh screen in order for the glue mix to be smoothly transferred from the storage tank to the glue mix applicator.