X-ray tomography has been shown to provide insights into the internal structure of whole cells that can't be obtained by any other means. With recent advances in instrumentation and the advent of automated cryogenic sample stages, it has become possible to collect isotropic tomographic data from radiation-sensitive cells and to compute reconstructions with a high degree of fidelity to a resolution of 50 nm. The new generation of X-ray optics will extend this resolution limit to 15 nm or better. The development of X-ray tomography of whole cells generates opportunities to study cells, and cellular processes, in a completely new way.