The structure of pyrocarbon and pyroboroncarbon were studied by a combination of electron microscopy techniques including electron diffraction, electron energy-loss spectroscopy, high-resolution, bright-/dark-field and secondary electron images at different length scales. Both materials are characterized by the turbostratic structure with the inclusions of soot particles in pyrocarbon and monocrystallites of two types in pyroboroncarbon. It has been found that within domains with dimensions about 1 μm the basic atom planes of the turbostratic structure are predominantly aligned in a certain direction. In the neighboring domains the basic planes have different predominant orientations such that the whole structure is isotropic. Only in pyroboroncarbon inside these domains there are local regions in which the orientation of basic planes deviated from the predominant orientation that are apparently depended on the monocrystallites inclusions.