In this paper, we report the accurate estimation of vine grape yield from a three-dimensional radar imagery technique. Three ground-based frequency-modulated continuous-wave radars operating respectively at 24GHz, 77GHz and 122GHz are used for the contact-less estimation of grape mass in vineyards. 3D radar images are built from the beam-scanning of the vine plants and allow estimating the mass of grapes from the computation of appropriate statistical estimators. These estimators are derived from the measured polarization and magnitude of radar echoes. It is shown that the estimation of grape mass from the proposed ground-based radar imagery technique at millimeter-wave frequency range may be accurate within 1 per cent.