RNase P is a universal ribozyme involved in RNA processing, in particular the maturation of the 5′ end of tRNA. Unlike most naturally occurring ribozymes, it recognizes and cleaves its substrate in trans and is capable of multiple turnovers. RNase P is a ribonucleoprotein complex containing one RNA subunit and as few as one protein subunit. The RNA subunit alone can support catalysis in vitro. In recent years, structures of the specificity domain and of the entire RNA component of RNase P from two different bacteria have been described and provide the first atomic level information on the structure of the RNA component. Structures of the protein component of different bacteria as well as the structures of several of the protein components of archaeal organisms have also been elucidated. Despite all these structural studies of the RNA component and the protein components, the catalytic mechanism of action and the way RNase P recognizes its substrate are still not fully understood at the atomic level. Nevertheless, all these structures start to provide an atomic level understanding of the architecture of RNase P and help to clarifying the relationships between RNase P from all organisms.