Crystallization and preliminary characterization of the essential dengue virus NS3 serine protease complexed with a Bowman-Birk-type inhibitor from mung beans are reported. As the structure proved resistant to solution by molecular replacement and multiple isomorphous replacement methods, multi-wavelength anomalous diffraction data at the LIII edge of a holmium derivative have been measured. Promising Bijvoet and dispersive signals which are largely consistent with expected values have been extracted from the data. The structure, when determined, will provide a structural basis for the design, synthesis and evaluation of inhibitors of the protease for chemotherapy of dengue infections.