Background Dengue is the most prevalent arboviral disease of humans. Virus neutralizing antibodies are likely to be critical for clinical immunity after vaccination or natural infection. A number of human monoclonal antibodies (mAbs) have previously been characterized as able to neutralize the infectivity of dengue virus (DENV) for mammalian cells in cell-culture systems. Methodology/Principle findings We tested the capacity of 12 human mAbs, each of which had previously been shown to neutralize DENV in cell-culture systems, to abrogate the infectiousness of dengue patient viremic blood for mosquitoes. Seven of the twelve mAbs (1F4, 14c10, 2D22, 1L12, 5J7, 747 (4)B7, 753(3)C10), almost all of which target quaternary epitopes, inhibited DENV infection of Ae. aegypti. The mAbs 14c10, 747(4)B7 and 753(3)C10 could all inhibit transmission of DENV in low microgram per mL concentrations. An Fc-disabled variant of 14c10 was as potent as its parent mAb. Conclusions/Significance The results demonstrate that mAbs can neutralize infectious DENV derived from infected human cells, in the matrix of human blood. Coupled with previous evidence of their ability to prevent DENV infection of mammalian cells, such mAbs could be considered attractive antibody classes to elicit with dengue vaccines, or alternatively, for consideration as therapeutic candidates.