"Republikflucht" ("desertion from the republic") and "Republikflüchtling(e)" ("deserter(s) from the republic") were the terms used by authorities in the German Democratic Republic (GDR – East Germany) to describe the process of and the person(s) leaving the GDR for a life in West Germany or any other Western (non-Warsaw Pact) country (Eastern Bloc emigration and defection).
The term applies both to the mass desertion of millions who could leave the GDR rather easily before the Berlin Wall was erected on 13 August 1961, as well as those few thousands who made a dangerous attempt to cross over the Iron Curtain (e.g. the Berlin Wall, the Inner German border, or the western border of another country of the Eastern Bloc), or who managed to obtain temporary exit visas and subsequently did not return, from 1961 to 1989.
Some estimates put the number of those who left the Soviet sector of Berlin, the Soviet occupation zone, and the GDR between 1945 and 1961 between 3 and 3.5 million. Close to one million of those who left were refugees and expellees from World War II and the post-war era initially stranded in the Soviet zone or East Berlin.
The numbers leaving the GDR following the construction of the Wall dropped sharply to several hundred a year as an attempt to flee the GDR via its fortified borders involved considerable personal risk of injury or death (see: List of deaths at the Berlin Wall). Several hundred Republikflüchtlinge were shot; about 75,000 were caught and imprisoned.
A propaganda booklet published by the Socialist Unity Party of Germany (SED) in 1955 for the use of party agitators outlined the seriousness of "flight from the republic":
Both from the moral standpoint as well as in terms of the interests of the whole German nation, leaving the GDR is an act of political and moral backwardness and depravity.
Those who let themselves be recruited objectively serve West German Reaction and militarism, whether they know it or not. Is it not despicable when for the sake of a few alluring job offers or other false promises about a "guaranteed future" one leaves a country in which the seed for a new and more beautiful life is sprouting, and is already showing the first fruits, for the place that favors a new war and destruction?
Is it not an act of political depravity when citizens, whether young people, workers, or members of the intelligentsia, leave and betray what our people have created through common labor in our republic to offer themselves to the American or British secret services or work for the West German factory owners, Junkers, or militarists? Does not leaving the land of progress for the morass of an historically outdated social order demonstrate political backwardness and blindness? ...
[W]orkers throughout Germany will demand punishment for those who today leave the German Democratic Republic, the strong bastion of the fight for peace, to serve the deadly enemy of the German people, the imperialists and militarists.
Article 213 of the GDR Penal Code of 1979 also made it quite clear that crossing the border without first obtaining government authorization would not be taken lightly:
- Anyone who illegally crosses the border of the German Democratic Republic or otherwise violates the regulations pertaining to temporary visits to the German Democratic Republic or transit through the German Democratic Republic will be punished with imprisonment of up to two years or sentenced to probation, detention, or a fine.
- Any citizen of the German Democratic Republic who in violation of the law does not return to the German Democratic Republic by the due date stated or who violates government guidelines for his stay abroad will likewise be punished.
- In case of aggravating circumstances, the perpetrator will be punished with imprisonment between one and eight years. Aggravating circumstances exist when the act endangers people's lives or health; is committed while carrying weapons or using dangerous means or methods; is executed with particular intensity; occurs by means of fraudulent alteration of documents, false notarization, or misuse of official documents or by using a hiding place; is committed in concert with others; the perpetrator has been sentenced for illegally crossing the border before.
- Preparation and attempts are both punishable under the law. 
The former East German party leader Erich Honecker was charged in 1993 for ordering soldiers to kill people trying to escape. The trial was postponed due to his bad health, and he died in 1994. Former Stasi chief Erich Mielke was also put on trial for the same charge. In November 1994, however, the presiding judge closed the proceedings, ruling that the defendant was not mentally fit to stand trial.
Refugees from the Soviet sector of Berlin, the Soviet zone, or East Germany could apply to be accepted as Vertriebene (expellees) of the sub-group of Soviet Zone Refugees (Sowjetzonenflüchtlinge) under the Federal Expellee Law (BVFG § 3), and thus receive support from the West German government. They must have fled before 1 July 1990 in order to rescue themselves from an emergency created by the political conditions imposed by the regime there, especially a danger for one's health, life, personal freedom, or freedom of conscience (BVFG § 3). The law did not apply for former supporters of the eastern political system of considerable influence, perpetrators against legality and humanity during the Nazi rule or afterwards within East Berlin or East Germany, and finally not for those who had fought against the democracy in West Germany or West Berlin (BVFG § 3 (2)).
- Rainer Münz, Where Did They All Come From? Typology and Geography of European Mass Migration In the Twentieth Century, presented at the "European Population Conference/Congrès Européen de Démographie" (United Nations Population Division), Milano, 4–8 September 1995, p. 2.2.1.
- Senate Chancery, Governing Mayor of Berlin, The construction of the Berlin Wall Archived 2014-04-02 at the Wayback Machine. states: "Between 1945 and 1961, around 3.6 million people left the Soviet zone and East Berlin."
- Pertti Ahonen, After the expulsion: West Germany and Eastern Europe, 1945–1990, Oxford: Oxford University Press, 2003, p. 274. ISBN 0-19-925989-5.
- "Wer die Deutsche Demokratische Republik verläßt, stellt sich auf die Seite der Kriegstreiber" [He Who Leaves the German Democratic Republic Joins the Warmongers]. Notizbuch des Agitators ("Agitator's Notebook") (in German). Socialist Unity Party of Germany, Agitation Department, Berlin District. November 1955. Retrieved 2008-02-17.
- Ministerium der Justiz (Ed.). (1979).Strafgesetzbuch der Deutschen Demokratischen Republik --StGB--. Textausgabe mit Sachregister. Berlin (East): Staatsverlag der Deutschen Demokratischen Republik.
- "Ex-Chief of E. German Secret Police Freed : Europe: Court releases Erich Mielke. He served time for 1931 killings--but not for any crime from Communist era." Los Angeles Times, August 2, 1995.
- Volker Ackermann, Der „echte“ Flüchtling. Deutsche Vertriebene und Flüchtlinge aus der DDR 1945 - 1961, Osnabrück: 1995 (= Studien zur historischen Migrationsforschung; vol. 1).
- Henrik Bispinck, "„Republikflucht“. Flucht und Ausreise als Problem der DDR-Führung", in: Dierk Hoffmann, Michael Schwartz, Hermann Wentker (eds.), Vor dem Mauerbau. Politik und Gesellschaft der DDR der fünfziger Jahre, Munich: 2003, pp. 285–309.
- Henrik Bispinck, "Flucht- und Ausreisebewegung als Krisenphänomene: 1953 und 1989 im Vergleich", in: Henrik Bispinck, Jürgen Danyel, Hans-Hermann Hertle, Hermann Wentker (eds.): Aufstände im Ostblock. Zur Krisengeschichte des realen Sozialismus, Berlin: 2004, pp. ??
- Bettina Effner, Helge Heidemeyer (eds.), Flucht im geteilten Deutschland, Berlin: 2005
- Helge Heidemeyer, Flucht und Zuwanderung aus der SBZ/DDR 1945/49-1961. Die Flüchtlingspolitik der Bundesrepublik Deutschland bis zum Bau der Berliner Mauer, Düsseldorf: 1994 (= Beiträge zur Geschichte des Parliamentarismus und der politischen Parteien; vol. 100).
- Damian van Melis, Henrik Bispinck (eds.), Republikflucht. Flucht und Abwanderung aus der SBZ/DDR 1945-1961, Munich: 2006.