The performance characteristics of immunoassay systems are dependent to extent on the binding characteristics of the immunoreactants utilized. For this investigators involved in the use of immunoassay systems for the detection of bial antigens have been particularly interested in the evolving technology re] the production and development of monoclonal antibodies (Kennet et al. 1980; Kohler and Milstein 1975; Steinitz et al. 1977). The potential advantages of monoclonal antibodies for immunoassay systems are numerous (Table 1). For example, a consistent supply of a well-defined reagent should allow for the wide-scale availability of immunoassay systems with defined performance characteristics. In addition, since immunoassays follow the law of mass action (Table 2), the availability of immunoglobulin preparations with every molecule directed against antigen should improve the kinetics and thus the sensitivity of immunoassay systems (Yolken 1982). This is especially true in the case of solid-phase immunoassays since the concentration of immunoglobulin which can be utilized in these systems is limited by the binding properties of the solid phase. The specificity of the monoclonal antibodies also allows the utilization of competitive and homogeneous immunoassays which are difficult, if not impossible, to perform with polyclonal antibodies due to the high amount of non-reactive immunoglobulin in such preparations. In addition, the specificity of monoclonal antibodies allows the performance of specific serotyping reactions and measurements of antigenic variations using fairly simple procedures.