Scaling behaviors of ZnO transparent thin-film transistors (TTFTs) have been studied by fabricating series of miniaturized ZnO TTFTs having various channel widths and lengths. Mobility of >8cm2∕Vs and on/off ratio of up to 107 are achieved with these TTFTs. Results show that these ZnO TTFTs retain rather well-behaved transistor characteristics down to the channel length of ∼5μm, rendering possible high-resolution applications. More apparent short-channel effects (e.g., lowering of threshold voltages, degradation of the subthreshold slope with the decrease of the channel length and the increase of the drain voltage, loss of hard saturation, etc.) are observed when the channel length is reduced below 5μm.