Electrical properties of ZnO nanowires and intramolecular p–n junctions were characterized by I–V measurements. These nanowires were grown embedded in anodic aluminum oxide (AAO) templates by vapor-phase-transport growth method. The nanowires were dense, continuous, and uniform in diameter along the length of the wires. I–V measurements showed the average resistivity of the ZnO nanowires in AAO templates was about one order of magnitude higher than that of the naked single ZnO nanowire. The p–n junctions in ZnO nanowires were fabricated by a two-step growth of ZnO with and without dopant of boron (∼1 wt %) in the source. I–V results suggested that p–n junctions in ZnO nanowires were formed by the two-step method.