This study investigates the improvement in above ground biomass estimates when using a synergistic model based on lidar derived forest structural information (i.e., canopy cover percentage) and radar backscatter. The results were cross-compared with a radar only model. A two-layered radar backscatter model was also tested. The results showed that lidar-based structural information has the potential to increase the accuracy of biomass estimation by up to 20% depending on polarization and acquisition date. A smaller improvement was observed when using a modeled estimate of the forest canopy cover as would be the case of a future lidar/radar joint space-borne mission. The two-layered vegetation backscatter model did not improve the biomass estimation accuracy with errors being higher when compared to a single-layer vegetation model.