This book can be used as a review guide for the students preparing for exams in medical or science disciplines. The first two chapters focus on the disorders of carbohydrate metabolism and the diseases of lipids metabolism. The third chapter highlights the diseases of protein metabolism including different forms of phenylalanemia, tyrosinemia, alkaptonuria and various urea cycle disorders. The fourth chapter discusses the diseases associated with nucleic acids metabolism such as gout and Lesch-Nyhan syndrome. The last two chapters are dedicated to concise but useful information on molecular genetics and various instrumental techniques used in a clinical diagnostic laboratory. An overview of respective macromolecules metabolism is also presented at the beginning of each chapter for a better understanding of the subject.