Crystals of rhinovirus 14 have been grown reproducibly. They diffract x-rays to a resolution of at least 3.5 A. The orthorhombic crystal unit cell contains two virions, each situated on a crystallographic twofold axis. At less than 30-A resolution, the space group approximates to 1222 with the particles possessing 222 pseudo crystallographic symmetry. The crystals are "isomorphous" with type I polio crystals [Finch, J. T. & Klug, A. (1959) Nature (London) 183, 1709-1714; Hogle, J. M. (1982) J. Mol. Biol. 160, 663-668], suggesting some similarities of structure between enteroviruses and rhinoviruses.