GaN epitaxial layers and InGaN/GaN multiquantum well blue light emitting diodes (LEDs) were prepared on both patterned sapphire substrates (PSS) and conventional sapphire substrates. From scanning electron microscopy micrographs of GaN epitaxial layers on PSS, it was found that lateral growth indeed occurred and the lateral to vertical growth rate ratio was around 2. It was also found that we could enhance the LED output power by using lateral epitaxial patterned sapphire. Such an enhancement could be attributed to the reduced dislocation density in the lateral growth regions of the epitaxial layers. (C) 2003 Elsevier B.V. All rights reserved.