Length control of ZnO nanowire arrays is a valuable concern for both fundamental research and future device application. In this article, vertically aligned ZnO nanowire arrays were synthesized by a seed layer catalyzed vapor phase transport method in a single experiment cycle. The length of these nanowire arrays exhibits a quasi-continuous evolution. It was found that the type and flow rate of carrier gas have a significant influence on the length modulation of ZnO arrays along the tube. A feasible route to tune the length of ZnO nanowire arrays from several micrometers to nearly 100 mu m could be achieved by adjusting proper deposition position and carrier gas. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.