Major developments continue to be reported in key areas of immunoassay technology. Following the development of excellent signal generation methods, attention has shifted to the development of immunochemical methods and instrumentation to provide convenient systems of high performance. Important advances have been made in the design of immunochemical approaches that permit the replacement of competitive format assays for small molecules, such as drugs, metabolites and pollutants, with non-competitive formats, bringing advantages previously seen only with large molecular analytes. Bispecific antibodies and recombinant proteins are also beginning to impact immunodiagnostics, with the promise of even more highly specified reagents. Improvements in automation have brought the facility of homogeneous systems to high-throughput and high-performance heterogeneous systems. Similarly, 'point of need' testing continues to progress. Through all of these advances, systems are evolving according to the needs of users in terms of operator convenience, accuracy, specificity, speed, robustness, and sensitivity.