Methods for antibiotic residue detection in dairy products, especially raw milk, have greatly improved as to their rapidity, accuracy and sensitivity over the past 30 years. An assay requiring overnight coagulation was available in the mid-1950's, whereas now there is an immunologically-based test using monoclonal antibody technology requiring only 6 min. These advances have not come about without extensive research efforts. The following is an overview of the developments and their significance to the dairy industry.