African swine fever (ASF) is endemic in some parts of eastern and southern Africa. The introduction of ASF into free areas leads to losses because of the devastating effects it causes. In order to minimise these losses, it is essential that there is a strong early warning and early reaction capacity. The key to such a system is disease recognition. The purpose of this manual is to enhance recognition of ASF at all levels for early warning and early reaction, so that the disease can be identified and eliminated at its earliest appearance in any area. Special attention has been given to the clinical, anatomical and pathological similarity of African swine fever with classical swine fever.