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.

An alternative choice to commemorate the reunification could have been the day the Berlin Wall came down—November the 9th, 1989, which coincided with the anniversary of the proclamation of the German Republic in 1918 and the defeat of Hitler's first coup in 1923. However, 9 November was also the anniversary of the first large-scale Nazi-led pogroms against Jews in 1938 (Kristallnacht), so the day was considered inappropriate as a national holiday. Therefore, 3 October 1990, the day of formal reunification, was chosen instead.