The Day of German Unity (German: Tag der Deutschen Einheit) is the national day of Germany, celebrated on 3 October as a public holiday. It commemorates the anniversary of German reunification in 1990, when the goal of a unity of Germany that originated in the middle of the 19th century, was fulfilled. Therefore, the name addresses neither the re-union or union but the unity of Germany. The Day of German Unity on October 3 has been a German national holiday since the reunification in 1990, when the German reunification was brought out in full force. The 3rd of October is a legal holiday of the Federal Republic of Germany.

The Day of German Unity is at the same time an anniversary for the re-founding of the five states Brandenburg, Mecklenburg-Vorpommern, Saxony, Saxony-Anhalt and Thuringen.