This paper presents the results of the comparisons between vertical backscatter profiles of forest measured by the HUTSCAT scatterometer and simulated profiles using a radiative transfer model. The objective is to validate the model using the measurements. The vertical forest backscatter profiles at near vertical incidence, at X-band and for 3 polarisations, are compared with the output from the MIT/CESBIO RT model coupled with a tree growth architectural model. An a posteriori correction is introduced to estimate correctly the backscatter coming from the lower parts of the trees. The measurements and simulated profiles are in good agreement and show that the wave interacts more profoundly within the canopy than expected, even at X-band