Polymerase chain reaction (PCR) is an in vitro technique in which a specific DNA segment extending between two known parts of a deoxyribonucleic acid (DNA) chain is enzymatically amplified and is becoming more widespread every day. The PCR method is used for many purposes such as diagnostic, epidemiological and DNA quantity determination studies and continues to be developed. The field of microbiology continues to develop by receiving a significant share of the developments in all areas where PCR is used. PCR, which is used for many purposes for pathogenic microorganisms of human and animal origin, also forms the basis of many molecular methods used today. Regardless of the purpose of the reaction, the reagent and PCR parameters to be used must be optimized for each gene region. In fact, the optimization may need to be repeated even between different instruments and laboratories where PCR will be performed. In this review, the use of PCR in microbiology, the main standards that should be followed when designing PCR and in the reagents and materials used in all stages of PCR will be discussed.