Photoassisted epitaxy of ZnTe on GaAs by a metal organic vapour-phase process has been performed using sources of diethylzinc and diethyltellurium or diisopropyltellurium. Illuminating the layer during growth with a xenon lamp increases the growth rate. Growth rate enhancement was found to be a function of light wavelength and intensity. Only photons having energy higher than the bandgap of ZnTe increase the growth rate. The characterization of the layers by X-ray diffraction and of the surface morphology by Nomarski microscopy is reported. We observed the degradation of the surface morphology of irradiated layers in comparison with unilluminated layers. We tentatively explain the growth rate enhancement by a photocatalytic surface process involving electron-hole pairs created in the ZnTe layers.