The development of molecular techniques, particularly the use of the polymerase chain reaction, has transformed the detection of infectious diseases (PCR). Because of the method's great sensitivity and ease of use in detecting any known DNA sequence, it has found widespread use in the biological sciences. Real-time PCR assays have lately made significant contributions, with the addition of a fluorescent probe detection system resulting in increased sensitivity over conventional PCR, the ability to confirm the amplifcation product, and the capacity to quantify the target concentration. Furthermore, nucleotide sequence analysis of the amplifcation products has aided epidemiological studies of infectious disease outbreaks and the monitoring of infection treatment outcomes, particularly for viruses that mutate often. The applications of qualitative and quantitative real-time PCR, nested and multiplex PCR, nucleotide sequence analysis of amplifed products, and quality assurance with nucleic acid testing (NAT) in diagnostic laboratories are discussed in this study.