In this article, we present a method of patterning a GaN substrate using polystyrene spheres and its inversed structure as the mask. By dry etching, different surface morphologies and depths of the GaN substrate can be obtained by changing the etching time. We used such a sphere-patterned GaN substrate to fabricate GaN-based light-emitting diodes (LED). It was found that the total lighting output of the sphere-patterned GaN LED was increased by 37%. (C) 2009 The Japan Society of Applied Physics