To enhance the light extraction efficiency of the GaN-based light emitting diode (LED), indium tin oxide (ITO) nanoparticle photonic crystal patterns are fabricated on the surface of the GaN-based blue LED device using the direct printing technique of the ITO nanoparticles. According to electroluminescence (EL) measurements, the EL intensity of the GaN-based blue LED with photonic crystal patterns is 28% higher than an identical LED without photonic crystal patterns. Printing the ITO nanoparticles eliminates the need for a plasma etching process of the ITO layer so that the current-voltage characteristics do not degrade. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3489293] All rights reserved.