Lateral epitaxial overgrowth (LEO) of GaN layers has been achieved on 3 μm wide and 7 μm spaced stripe windows contained in SiO2 masks on GaN/AIN/6H-SiC(0001) substrates via organometallic vapor phase epitaxy (OMVPE). The extent and microstructural characteristics of lateral overgrowth were a complex function of stripe orientation, growth temperature and triethylgallium (TEG) flow rate. A high density of threading dislocations, originating from the interface of the underlying GaN with the AIN buffer layer, were contained in the GaN grown in the window regions. The overgrowth regions, by contrast, contained a very low density of dislocations. The second lateral epitaxial overgrowth layers were obtained on the first laterally grown layers by the repetition of SiO2 deposition, lithography and lateral epitaxy.