The influence of the mechanical rubbing of a polyimide (PI) film on the laser-induced periodic structure (LIPS) was demonstrated. The periodicity and amplitude of LIPS were greater when the rubbing direction was parallel to the laser polarization direction. The amplitude became small and the periodicity of LIPS did not show an obvious change when the rubbing direction was perpendicular to the laser polarization direction. The effect of the rubbing pretreatment on LIPS was explained on the basis of the wave-guide effect of rubbing-induced microgrooves on LIPS formation. The orientation of PI chains induced by mechanical rubbing was relaxed after laser irradiation, and a new orientation of PI chains was formed during the LIPS formation. When the rubbing direction was perpendicular to the laser polarization direction, the orientation of PI chains remained in the rubbing direction. The laser-irradiated, perpendicularly rubbed PI surface could be used to verify the effects of surface morphologies and intermolecular interactions on liquid-crystal alignment. (C) 2003 Wiley Periodicals, Inc.