We show that the nonlinear optical activity of an organic molecule may be quenched by electron irradiation. Exploiting this effect, we inscribe periodic χ(2) patterns in the molecular films by means of a scanning electron microscope. The second harmonic diffraction efficiency of the resulting χ(2) gratings is measured. The relative intensity of the diffraction orders observed agrees with the expectations for a sheet of nonlinear dipoles with a periodic modulation. No linear diffraction is seen. The present method allows realizing any type of two-dimensional χ(2) pattern with a resolution only limited by the electron beam patterning capabilities.