Electron microscopy (EM) is indispensable when it comes to the analysis of ultrastructural elements of biological material. However, the right preparation is necessary so that biological samples withstand vacuum and radiation inside an electron microscope without changes in ultrastructure. Chemical fixation can be considered the most classical approach. Fixatives are used to crosslink proteins as well as lipids to retain the original structure and stains are added for increased contrast. It is a relatively easy and cost effective procedure. On the other hand, high-pressure freezing offers a more physical approach to structural preservation. Exertion of a very high pressure during rapid freezing in liquid nitrogen hinders the expansion of ice crystals and thus the damage to cellular material. The sample subsequently undergoes a process called freeze substitution in which frozen water is replaced by liquid solvents and fixatives while slowly warming up to 0C. The optimal method of preparation varies by sample and structure of interest. To establish a comparison, tissue and cell cultures from various organisms were prepared and the quality of the ultrastructure compared. High-pressure frozen samples typically showed smoother membranes and better preservation of mitochondria. Chemically fixed samples demonstrated better fixation of neuronal components but a higher likelihood of faulty resin infiltration.