We have successfully synthesized vertically aligned ZnO nanotube arrays by metalorganic chemical vapor deposition. Since no metal catalysts are used in this work, the growth process of ZnO nanotube arrays does not follow a vapor-liquid-solid mechanism but a self-catalyzed growth mechanism. X-ray diffraction results show that the nanotubes have ZnO hexagonal wurizite structures and only the ZnO (0002) peak can be seen. The rocking curve also shows a full width at halfmaximum value of ∼1625 arc second. A 6-fold symmetry in Ø-scan data is also observed, indicating in-plane alignment of ZnO nanotube arrays. Room, temperature photoluminescenee results present a high optical quality and nearly defect-free crystal structure of ZnO nanotube arrays. Moreover, the high near-band edge emission to deep level emission intensity ratio (INBE/IDLE) of 2050 is obtained.