Particle image velocimetry (PIV) has been used to experimentally study the velocity field during the discharge of a monolayer of monodisperse granular material (composed of 3 mm-diameter glass beads) in silos with different geometries. Silos were rectangular with the exit port located in the center or close to the lateral wall, and a convergent silo with angle øw = 60.. In all cases we characterized the mean velocity profiles and the fluctuation intensities. For silos with the exit port located at the center (symmetrical configurations), strong flow oscillations were detected, but not for the nonsymmetrical configuration. This last result is a strong indication that the mass flow rate is lower in the symmetrical silos. A simple theory was given for stationary flow in convergent silos and its corresponding parameters were calculated from experimental data. Numerical simulations show good agreement with measured velocity fields.