This study presents how Mualem-van Genuchten (M-vG) hydraulic parameters of a sandy soil can be obtained from ground-penetrating radar data acquired during water infiltration down a tube placed in a vertical hole. Water content profiles were simulated at various infiltration time steps using SWMS-2D based on initial values of the M-vG parameters and were converted to dielectric permittivity profiles using the Complex Refractive Index Model. The GprMax2D suite of programs was used to generate radargrams showing the electromagnetic reflections on the simulated wetting bulb. The shuffled complex evolution algorithm was used to estimate the M-vG parameters from GPR reflections measured during a constant head borehole infiltration. The method is presented on synthetic examples and on field experiments carried out in a sandy soil. The estimated parameters were compared with values obtained in laboratory on soil samples and with disk infiltrometer measurements.