Skin alterations can be caused by both environmental conditions and diseases of the organism. Some diseases may only manifest in the skin while others represent signs of a generalized infection. Regarding their origin, skin diseases can be divided into congenital, infectious, and nutritional disorders, and those resulting from housing scarcities. Additionally, there are skin diseases with unknown causes. Skin diseases in a swine herd can result in economic losses through decreased feed efficiency and growth rate and increased mortality. The knowledge of causes and symptoms as well as the selection of appropriate further laboratory investigations provide a valid diagnosis and enable a quick and effective therapy. This description of several skin diseases should provide a background.