An enzyme linked immunosorbant assay (ELISA) incorporating mouse anti-human IgE monoclonals as capture and secondary antibodies has been tested for measurement of total IgE in human serum samples. Reagents tested have provided accurate, reproducible readings using an in-house standard human serum pool with known IgE content. Sera obtained from JEV reactors participating in the U.S. Navy immunization program and from JEV reactors immunized in Denmark have been examined for total IgE content. Pre and post-immunization sera obtained from plague vaccine immunized individuals have also been examined for total IgE. Assay development for detection of specific IgE to vaccines and vaccine components has been initiated. Detection of plague vaccine specific IgE has been indicated in limited assays.