Diverse human disorders, including the majority of neurodegenerative diseases, are thought to arise from the misfolding and aggregation of protein. We have recently described a novel technology to amplify cyclically misfolded proteins in vitro. This procedure, named protein misfolding cyclic amplification (PMCA), is conceptually analogous to DNA amplification by PCR and has tremendous implications for research and diagnosis. The PMCA concept has been proved on the amplification of prions implicated in the pathogenesis of transmissible spongiform encephalopathies. In this article we describe the rational behind PMCA and some of the many potential applications of this novel technology.