Berne virus (BEV) is the protopype member of the torovirus genus and the only torovirus that can be grown in tissue culture. Torovirus genome consists of 6 ORFs, ORFs 1a and 1b, comprising the 5’-most two-thirds of the genome, and four additional ORFs encoding the structural proteins S, M, N, and HE. In BEV, ORF4, corresponding to the HE protein, the gene found in the bovine and porcine isolates. A distinct characteristic of the torovirus particles is the high morphological variability that they exhibit once they are released from infected cells. Spherical, oval, elongated, and kidney-shaped virions can be torovirus morphogenesis is still poorly understood and further studies are required to characterize this process at both morphological and molecular levels as well as to understand the structure of torovirus particles. All the information about the structure and morphogenesis of toroviruses comes from early studies performed by conventional electron microscopy examination of thin sections from cultured equine dermis cells infected with BEV, 1, 2 as well as from intestinal tissue from calves infected with the bovine torovirus BRV. 3 These studies provided detailed descriptions of the different viral assemblies. However, in the past two decades new methods for structural analysis by ultrastructure of cellular and viral components. Freeze-substitution is one of these high preservation methods that has been shown to greatly reduce artifactual changes in shape and size that can occur during fixation and dehydration of the sample when conventional treatments are used. Thus, in this work, BEV infected cells were fixed and treated by this technique to examine torovirus particles in the context of infected cells. To perform a