Recent events such as the 2009 pandemic influenza outbreak, the continuous spread of African swine fever virus in Eastern Europe and the introduction of several new pathogens into the United States and their spread to Canada, Mexico, Central and South America have emphasized the ability of pig diseases to cross borders rapidly and the importance of global cooperation to improve the health and welfare of pigs. This chapter summarizes recent research on the causes and epidemiology of major bacteria, viruses and parasites found in pig production, focusing on those with a particular impact on safety  and global production.