The Munich Agreement (Czech: Mnichovská dohoda; Slovak: Mníchovská dohoda; German: Münchner Abkommen) was an agreement concluded at Munich on 30 September 1938, by Nazi Germany, the United Kingdom, France, and Italy. The agreement provided for the German annexation of land on the border between Czechoslovakia and Germany called the Sudetenland, where more than three million people, mainly ethnic Germans, lived. The pact is also known in some areas as the Munich Betrayal (Czech: Mnichovská zrada; Slovak: Mníchovská zrada), because of a previous 1924 alliance agreement and a 1925 military pact between France and the Czechoslovak Republic.

Germany had started a low-intensity undeclared war on Czechoslovakia on 17 September 1938. In reaction, the United Kingdom and France on 20 September formally asked Czechoslovakia to cede its Sudetenland territory to Germany, which was followed by Polish territorial demands brought on 21 September and Hungarian on 22 September. Meanwhile, German forces conquered parts of Cheb District and Jeseník District, where local battles included use of German artillery and Czechoslovak tanks and armored vehicles. Lightly armed German infantry also briefly overran, but was repelled from dozens of other border counties. Poland also grouped its army units near its common border with Czechoslovakia and conducted unsuccessful probing offensive on 23 September. Hungary also moved its troops towards the border with Czechoslovakia, without attacking.

An emergency meeting of the main European powers – not including Czechoslovakia, although their representatives were present in the town, or the Soviet Union, an ally to both France and Czechoslovakia – took place in Munich, Germany, on 29–30 September 1938. An agreement was quickly reached on Hitler's terms, and signed by the leaders of Germany, France, Britain, and Italy. The Czechoslovak mountainous borderland that the powers offered to appease Germany had not only marked the natural border between the Czech state and the Germanic states since the early Middle Ages, but it also presented a major natural obstacle to any possible German attack. Having been strengthened by significant border fortifications, the Sudetenland was of absolute strategic importance to Czechoslovakia.

On 30 September, Czechoslovakia yielded to the combination of military pressure by Germany, Poland, and Hungary, and diplomatic pressure by the United Kingdom and France, and agreed to give up territory to Germany on Munich terms. Then, on 1 October, Czechoslovakia also accepted Polish territorial demands.

The Munich Agreement was soon followed by the First Vienna Award on 2 November 1938, separating largely Hungarian inhabited territories in southern Slovakia and southern Subcarpathian Rus' from Czechoslovakia. On 30 November 1938 Czechoslovakia ceded to Poland small patches of land in Spiš and Orava regions.

In March 1939, the First Slovak Republic, a Nazi puppet state, proclaimed its independence. Shortly afterwards, Hitler reneged on his solemn promises to respect the integrity of Czechoslovakia by invading Czechia and turning it into the Protectorate of Bohemia and Moravia, giving Germany full control of what remained of Czechoslovakia, including its significant military arsenal that later played an important role in Germany's invasions of Poland and France. As a result, Czechoslovakia had disappeared.

Much of Europe celebrated the Munich Agreement, as they considered it a way to prevent a major war on the continent. Adolf Hitler announced that it was his last territorial claim in Northern Europe. Today, the Munich Agreement is widely regarded as a failed act of appeasement, and the term has become "a byword for the futility of appeasing expansionist totalitarian states."