Antibody-enzyme conjugates are widely utilized in all spheres of specific analyte detection and measurement, and several trends are evident that will sustain, or even extend, this in the coming years. Of principal importance are the trends toward the development of simplified formats for the rapid and sensitive quantitation of a wide range of analytes without expensive or cumbersome instrumentation, and the exploitation of different types of enzyme and antibody molecules. Advances in hybridoma and recombinant genetics are enabling the practical manipulation of the theoretical repertoire of these reagents, facilitating their availability for a myriad of applications.