Microtubules are one of the three components of the eukaryotic cytoskeleton and play a central role in many aspects of cell function, including cell division and cell motility. Electron microscopy, of both isolated microtubules and of microtubules in their cellular context, is an essential tool in understanding their structure and function. These studies have been particularly important because the size and heterogeneity of microtubules mean that they are not readily studied by other structural methods. Electron microscopy at different levels of detail can bridge the gap between atomic resolution structures solved by X-ray crystallography or NMR, and the dynamic but relatively coarse information that is achieved in light microscopy experiments. This chapter provides an overview of current approaches to studying microtubules by electron microscopy. Negative stain studies can be relatively quick and easy, and provide a useful overview of microtubules and their interactions prior to undertaking more complicated experiments such as high resolution structure determination by cryo-electron microscopy or reconstruction of unique cellular entities by electron tomography. As more microtubule-associated proteins are uncovered, EM studies will make a significant contribution to our understanding of how these proteins influence microtubules and where in the cytoskeleton they act.