Diarrhea of pigs is one of the economically most significant disease complexes. Reduction in weight gain and a prolonged fattening period are the most serious consequences, which lead to financial losses and additional costs. Common causes of diarrhea of pigs are infectious diseases.Enteropathogenic agents are more significant, since they are usually followed by veterinary consultation and treatment. Within swine medicine many pathogens are well described as obligatory pathogenic agents. Bacteria, like enterotoxigenic Escherichia coli, Lawsonia intracellularis or Brachyspira are one of the most common causes for diarrhea in piglets. Nevertheless viruses and parasites must be taken into consideration for differential diagnosis. Besides known pathogens such as porcine circovirus 2 (PCV-2), rotavirus, porcine epidemic diarrhea virus (PeDV) and Cystoisospora suis, it is assumed that until now less regarded agents such as porcine astroviruses (PAstV), porcine kobuviruses (PKoV) and Neobalantidium coli may play an important role in diarrhea of pigs. Those pathogens are known in human medicine as diarrhea causing agents, especially in newborns, elderly people and people with weak immune system.