This book, ‘Modern Enzymology' is an attempt to review the basics of Enzymes with a further extension of their use in the modern era of biochemistry. The practical applications of enzymes in the diagnostic lab, food industry, and molecular biology are essential outputs developed by biochemists. In addition, the use of enzymes in clinical research is well emphasized. The astonishing growth in the research endeavor over the recent decade has multiplied the interest of researchers in diagnostic Enzymology. Online bioinformatics tools have well-equipped researchers in medical science where the diagnostic potential of enzyme level present in body fluid is obtained experimentally and confirmed with reactions in the diagnosis of disease. This approach is a practical introduction to Enzymology. Results obtained by researchers in the theoretical and practical aspects of Enzymology are consolidated here to benefit the students, teachers and researchers.