Research on filoviruses has been hampered by their status as biosafety level 4 pathogens. Previous investigations of filovirus structures within embedded, sectioned and metal-stained cells by electron tomography revealed few details of the high resolution oligomeric structure [16, 17] . It has been demonstrated that aldehyde-fixation alone, and subsequent cryo-electron microscopic imaging in the frozen-hydrated state preserves structures, at least up to 12 angstroms resolution [18] , and in some cases, fixation improves the resolution achievable [19] . In addition, it has also been shown that high-resolution X-ray structures can also be obtained in the presence of aldehyde fixatives [20] . Therefore, we analyzed purified and isolated EBOV and Ebola virus-like structures using cryo-electron microscopy (cryo-EM), and cryoelectron tomography (cryo-ET). In the current study, the Zaire strain of EBOV was purified and inactivated by paraformaldehyde fixation: excess fixative was then removed by dialysis to reduce beam damage for imaging in the frozen-hydrated state. The flashfreezing at liquid ethane temperatures used in cryo-electron microscopy preserves the structural and molecular detail, avoiding artifacts associated with conventional EM methods, such as dehydration and/or sectioning or staining, that usually prevent detailed structural analysis. Digital image processing reveals the 3D organization of EBOV, including the structural arrangement of component molecules at resolutions of 14-19 Å .