According to this study, tropical countries such as Cambodia require information about forest biomass to successfully implement climate change mitigation mechanism related to Reducing Emissions from Deforestation and Forest Degradation (REDD+). This study investigated the potential of Phased Array-type L-band Synthetic Aperture Radar Fine Beam Dual (PALSAR FBD) 50-m mosaic data to estimate Above Ground Biomass (AGB) in Cambodia. AGB was estimated using a bottom-up approach based on field measured biomass and backscattering (sigma(o)) properties of PALSAR data.