Simultaneous axial and radial epitaxies can be achieved on growing ZnO microtowers through a regrowth technique of repeating the same growth circle for several times. The as-grown ZnO microtowers display a preferential growth habit of hexagonal prism-dihexagonal pyramid. The apexes of the pyramidal towers are very sharp, with a radius of curvature as small as 2 to 50 nm.