The polymerase chain reaction (PCR) is another new powerful technique in molecular biology that has begun to open new perspectives in modern science and also in dermatology. This brief report will therefore elucidate the general principles of the polymerase chain reaction, as well as its limitations and possible pitfalls. Furthermore an overview will be provided on the impact of PCR on molecular biologic approaches in oncology, immunology, and human genetics. The use of the method as a tool to detect microorganisms particularly viruses and bacteria, in cutaneous tissue and it potential other future applications are described as well. Because PCR is automated and is being more and more established in routine laboratories, physicians and scientists should be familiar with the basic principles and potential uses of this methodology.