D J Mahad, A Hellden, J Jarvis, et al. Aciclovir induced posterior leucoencephalopathy (J Neurol Neurosurg Psychiatry 2005;76:1308–9). The authors of this letter were mistakenly grouped according to their affiliations. The correct ordering of the authors is: D J Mahad, A Helldén, J Jarvis, D Mitra, A Gholkar, P F Chinnery.