Prismatic zinc oxide microtubes have been fabricated by vapor transport. Room-temperature ultraviolet lasing action has been demonstrated in these microtube arrays. The ZnO microtubes, mainly appearing in tapped bell-mouthed shape, form natural laser cavities along the length direction. The hexagon diagonal and length of the microtube vary from 1 µm to 20 µm and 10 µm to a few hundred µm respectively. Under 355 nm optical excitation, lasing action is observed at room-temperature around 393 nm. Multi-longitudinal modes are also observed with significantly narrowed emission linewidth.