Uniaxially aligned vacuum deposited films of copper phthalocyanine (CuPc) have been studied by means of angle-dispersive grazing-incidence X-ray diffraction. The lateral structure of the top surface of a 100-nm-thick film was successfully probed. It was revealed that the microcrystals near the surface have a finite in-plane distribution with a full-width at half maximum of 17.5°. In-plane diffraction profiles were transformed into a reciprocal space map that reproduced the electron diffraction pattern of a CuPc thin film reported previously.