The Mycetozoa (also called plasmodial slime molds or myxogastrids) are a small group of kingdom Protoctista. Myxomycetes were classified in the kingdoms of Plantae and Animalia. Because, myxomycetes were typically found in the same habitats as fungi, considered as a taxon within the kingdom Fungi. Unlike fungi, myxomycetes do not excrete extracellular, digestive enzymes, and the myxomycetes do not play a role in the environment as decomposers or pathogens. Myxomycete comprises a relatively small and homogeneous group of amoeboid eukaryotic organisms, which lack a cell wall. Studies on myxomycetes are mostly carried out at taxonomic or systematic level. There are very few studies on the economic importance, their contribution to the ecological cycle, to be as food and medicine. Biochemical analysis results of myxomycetes made in the world gives hope for the future of humanity. Myxomycetes are one of the least discovered groups of organisms and fungi that can be seen macroscopically. The reproductive structures (fruiting bodies) produced by some Myxomycetes are usually large enough to be visible to the naked eye. Numerous examples are strikingly beautiful, and their colorful sparkling miniature structures attract the attention of biologists, researchers, instructors and students. Myxomycetes are also fascinating microscopic organisms. A person is very surprised to see a myxomycetes sporocarp or structure details of capillitium, columella, spore, etc. for the first time under a magnifying glass or microscope. The lack of scientists working on this subject and the difficulties in accessing the source caused people to not show interest in Mycetozoa. This book is the product of our many years of knowledge and joint effort on myxomycetes. There is a considerable amount of information in this book about the general structure, characteristics, history, diagnostic key, distribution and categories of mycetozoa. Our desire to compile and share our scientific results on Myxomycetes with local and foreign scientists led to the writing of this book. We have prepared a comprehensive book about Mycetozoa first time in Turkey by compiling all the work done so far in Turkey. Our aim is to provide an easily accessible resource to young researchers and scientists who will work on this subject.