Semiconductor GaN nanowires, sheathed with BN layers, were successfully synthesized by a simple chemical vapor deposition. The experimentally determined structure consists of a hexagonal wurtzite GaN core, and the outer shell of BN separated in the radial direction. The GaN-BN assembly-structure was about 40-50 nm in diameter and up to several hundreds of micrometers in length. The photoluminescence spectrum of the GaN-BN assembly-structure shows a very strong and broad blue-light emission, centered at 464 nm. The assembly-structures with semiconductor-insulator geometry, which take advantage of this self-organization mechanism for multi-element nanotube formation, have great prospects in fundamental physical science and applications in nanoscale optoelectronic devices (such as nanolasers). (C) 2003 Elsevier B.V. All rights reserved.