An ethnic war is a war between ethnic groups often as a result of ethnic nationalism. They are of interest because of the apparent prevalence in the aftermath of the Cold War and because they frequently result in war crimes such as genocide.

Two controversial questions about ethnic wars is are ethnic wars more prevalent in the post-Cold War period and whether ethnic wars are really about ethnicity at all. There are a number of political scientists who refer to the concept of ethnic wars as a myth becase they argue that the root causes of ethnic conflict do not involve ethnicity but rather institutional, political, and economic factors. These political scientists argue that the concept of ethnic war is misleading because it leads to the conclusion that certain groups are doomed to fight each other when in fact the wars between them are the result of political decisions.

A classic example of the reformulation of economic differences as ethnic differences is found in Rwanda. In a 1930s census, all people owning ten or more head of cattle were classified as Tutsi; everyone else was classified as Hutu.

See also ethnic conflict in India