We experimentally studied ultraviolet photoluminescence (PL) from ZnO (0001) single crystal at room temperature. The PL spectra taken from the sample edge show spectral width narrowing; lifetime shortening (100ps)and super linear intensity increase with pumping power, while the PL spectra taken from the sample surface only show broad spontaneous emission with a much longer lifetime (＞ 5 ns). These findings suggest that stimulated emission and lasing were only achieved at edges of the ZnO single crystal. Scanning-electron-microscopic images show a smooth sample surface morphology and a rougher morphology at the single crystal edge. Electron-hole plasma enhancement of gain may be attributed to the lasing effect observed from the sample edge.