Triatoma virus (TrV) is a viral pathogen of the blood-sucking reduviid bug Triatoma infestans, the most important vector of American human trypanosomiasis (Chagas' disease). TrV has been putatively classified as a member of the Cripavirus genus (type cricket paralysis virus) in the Dicistroviridae family. This work describes the purification of TrV particles from infected T infestans and their crystallization and preliminary crystallographic analyses. Two different crystal forms, rhombohedral and orthorhombic, were obtained at room temperature by the hanging-drop vapour-diffusion technique using polyethylene glycol and polyethylene glycol monomethylether as precipitants. The rhombohedral crystals have unit-cell parameters a = b = 306.6, c = 788.4 Angstrom (hexagonal setting), diffract to 3.2 Angstrom resolution and contain one-third of the viral particle per asymmetric unit. The orthorhombic crystals have cell parameters a = 336, b = 351, c = 332 Angstrom, diffract to about 2.5 Angstrom resolution, and contain one-half of a virus particle in the asymmetric unit. A complete diffraction data set has been collected to 3.2 Angstrom resolution, using synchrotron radiation, from a single rhombohedral crystal under cryogenic conditions.