Fondazione Human Technopole 1 article published in JoVE Biology Sample Preparation by 3D-Correlative Focused Ion Beam Milling for High-Resolution Cryo-Electron Tomography Anna Bieber*1, Cristina Capitanio*1, Florian Wilfling1,2, Jürgen Plitzko1, Philipp S. Erdmann1,3 1Max Planck Institute of Biochemistry, 2Max Planck Institute for Biophysics, 3Fondazione Human Technopole Here, we present a pipeline for 3D-correlative focused ion beam milling on guiding the preparation of cellular samples for cryo-electron tomography. The 3D position of fluorescently tagged proteins of interest is first determined by cryo-fluorescence microscopy, and then targeted for milling. The protocol is suitable for mammalian, yeast, and bacterial cells.