The paper presents the methods of obtaining transgenic animals and the purposes of genetic modifications with particular emphasis on the modifications of chemical composition and nutritional value of milk as well as on the modifications related to slaughter quality traits and quality of meat and fat. In November 2015, the American Food and Drug Administration (FDA) approved the production, sale, and consumption of genetically modified Atlantic AquAdvantage salmon characterized by a faster rate of growth and a better utilization of feed than its unmodified counterpart. AquAdvantage salmon is identical to Atlantic salmon, which is characterized in the FDA’s Reference Fish Encyclopaedia. As part of the safety evaluation, it was found that the nutritional profile of both salmon is comparable. In the paper, there are presented the principles of labelling the genetically modified products as are consumer attitudes towards genetically modified foods. Health and welfare of transgenic livestock is also described. It is imperative to develop appropriate tools to assess health risks and to continue more in-depth research studies on the effects of genetically modified animals on health and on their impacts on environment. There is a need to disseminate knowledge about genetically modified foods, which will certainly be accompanied by methodological progress and setting goals with real practical application. This is particularly important in the context of society’s attitudes towards genetically modified organisms (GMOs).