The light extraction enhancement of GaN-based flip-chip indium-tin oxide light-emitting diodes (FC ITO LEDs) with an inclined sidewall coated with TiO2/SiO2 omnidirectional reflectors (ODRs) is presented. At a driving current of 350 mA and a chip size of 1x1 mm, the light output power and the light extraction enhancement of the FC ITO LEDs coated TiO2/SiO2 ODRs with inclined sidewall reached 183 mW and 15% when compared with the results from the same device, FC ITO LEDs coated TiO2/SiO2 ODRs with vertical sidewall. Furthermore, by examining the radiation patterns of the FC ITO LEDs, the increased optical power within 150 degrees cone contributed to the stronger enhancement around the vertical direction of an inclined sidewall ODR within blue regime. Our work offers promising potential for enhancing output powers of commercial light-emitting devices. (c) 2007 The Electrochemical Society.