The polymerase chain reaction has revolutionized molecular biology by allowing the amplification and characterization of minute amounts of nucleic acids. As well as being of use to basic scientists, this technique is of immense importance to pathologists who routinely need to detect andcharacterize small amounts of infectious micro-organisms, or to identify mutations within small amounts of human DNA. This essential handbook outlines clearly and concisely the applications of PCR in the area of infectious and inherited diseases so that methods can be readily used by non-molecular biologists who need them.