The book "Clinical Applications of PCR" offers a comprehensive examination of the clinical applications of Polymerase Chain Reaction (PCR). It covers a variety of topics, including the detection of DNA methylation, the identification of viruses and protozoa in infectious diseases, and the estimation of gene copy number anomalies. Additionally, advanced techniques such as primer extension in conjunction with mass spectrometry and high-throughput NGS methods are discussed. The application of PCR has proven to be extremely valuable in genomics and transcriptomics, both for discoveries and routine clinical applications, forming the foundation of personalized medicine. The chapters are structured to provide a brief introduction to the respective topics, include a list of necessary materials and reagents, and offer step-by-step, easily reproducible laboratory protocols along with troubleshooting tips and advice on avoiding common pitfalls. This third edition is an essential guide for researchers seeking to understand the principles behind each application and aiming to implement them in the laboratory.