This article reports a novel hydrostatic pressure mechanism for soft UV imprinting. With this mechanism, the pressure distribution over the whole substrate is uniform. In addition, the nonuniform deformation of the soft mold during the imprinting process can be avoided. The mechanism employs a gasbag inside a closed chamber, which upon inflation compresses the whole polydimethylsiloxane (PDMS) mold/substrate stack not only from the surface but also from all the sides. The microstructures on the PDMS mold are then replicated onto photoresist-coated substrates. The result shows that the soft UV imprinting using a hydrostatic pressure mechanism can provide uniform pressure for imprinting. It also provides the hydrostatic pressure state on the stack so that micropatterns can be replicated with high fidelity from soft mold to photoresist on substrates. The accuracy of replication, even at the edge, has been experimentally verified. (c) 2008 American Vacuum Society.