<div><p>Introduction</p><p>Dengue is one of the most widespread mosquito-borne diseases in the world. The causative agent, dengue virus (DENV), is primarily transmitted by the mosquito <i>Aedes aegypti</i>, a species that has proved difficult to control using conventional methods. The discovery that <i>A. aegypti</i> transinfected with the <i>w</i>Mel strain of <i>Wolbachia</i> showed limited DENV replication led to trial field releases of these mosquitoes in Cairns, Australia as a biocontrol strategy for the virus.</p><p>Methodology/Principal Findings</p><p>Field collected <i>w</i>Mel mosquitoes that were challenged with three DENV serotypes displayed limited rates of body infection, viral replication and dissemination to the head compared to uninfected controls. Rates of dengue infection, replication and dissemination in field <i>w</i>Mel mosquitoes were similar to those observed in the original transinfected <i>w</i>Mel line that had been maintained in the laboratory. We found that <i>w</i>Mel was distributed in similar body tissues in field mosquitoes as in laboratory ones, but, at seven days following blood-feeding, <i>w</i>Mel densities increased to a greater extent in field mosquitoes.</p><p>Conclusions/Significance</p><p>Our results indicate that virus-blocking is likely to persist in <i>Wolbachia</i>-infected mosquitoes after their release and establishment in wild populations, suggesting that <i>Wolbachia</i> biocontrol may be a successful strategy for reducing dengue transmission in the field.</p></div>