The book of abstracts of the Fourth International Conference “Genetically modified organisms: The History, Achievements, Social and Environmental Risks” contains 38 abstracts covering a broad field of GMO research. Nowadays genetically modified organisms, their construction and study, are an essential part of many investigations as well as a part of modern agriculture. The results presented in the book are from different fields of research and performed on a broad range of organisms (plants, animals, fungi and algae).