Ribosomal proteins are subjected to a variety of post-translational modifications, of which methylation is the most frequently found in all three kingdoms of life. PrmA is the only bacterial enzyme identified to date that catalyzes the methylation of a ribosomal protein. It is responsible for the introduction of nine methyl groups into the N-terminal domain of ribosomal protein L11. The PrmA protein from Thermus thermophilus HB8 was crystallized and a preliminary X-ray diffraction analysis was performed. A cryocooled crystal diffracted X-rays beyond 1.9 A using synchrotron radiation.