Elongation factor P is a universally conserved protein stimulating peptidyltransferase activity during protein synthesis. The factor is sensitive to classical inhibitors of the ribosomal peptidyltransferase activity and is possibly involved in alignment of the substrate tRNAs in the catalytic centre of 70S ribosomes. Elongation factor P from the thermophilic Aquifex aeolicus was overexpressed as a soluble protein in Escherichia coli and crystallized. A fast generally applicable refolding protocol was developed to improve crystal quality and circumvent strong binding of oligonucleotides to the protein. Diffraction data collected to 2.7 A resolution present twinning.