This manual explains how to diagnose and respond to a case or outbreak of African swine fever (ASF). It includes general information on the disease and its causes, including epidemiology, transmission pathways and geographic distribution. It presents the different phases chronologically, from detection and diagnosis (clinical signs, postmortem findings and differential diagnosis) to laboratory confirmation (main techniques for detecting both virus and antibodies).African swine fever is a contagious viral disease that affects pigs of all ages, inducing a haemorrhagic fever. It is most often recognized in the acute form with an associated lethality of up to 100 percent, and is a severe threat to pig production systems. Not only does it threaten food security and challenge the livelihoods of pig producers and other actors in the supply chain, but it can have major consequences on international trade.Since there is currently no effective vaccine or treatment, the manual suggests that the best strategy for countries/zones that are still free of the disease is to prevent entry of the virus through improved border control, awareness-raising and better biosecurity. Infected countries will also need to be able to implement quick outbreak controls though movement restrictions and stamping-out policies.