Sinzendorf should not be confused with Zinzendorf (surname).
The House of Sinzendorf (also: Sinzendorff) was a German noble family with Upper Austrian origin (Sinzendorf in Nußbach), not to be confused with the Lower Austrian House of Zinzendorf. The family belonged to prestigious circle of high nobility families, but died out in 1822 in the male line.
The Sinzendorf family appear in the 13th century as Ministerialis of the Kremsmünster Abbey. The ancestral castle was Sinzendorf in the municipality Nußbach in Traunviertel. They owned Castle Feyregg from 1404 to 1566, and Castle Fridau from 1497 to 1708. Around 1450, the family split into two lines (later referred to as Ernstbrunn-Feyregg and Fridau - Neuburg). In 1592 Joachim von Sinzendorf bought the castle and fief of Ernstbrunn (with Klement Castle and Michelstetten Castle) and considerably expanded the Ernstbrunn Palace.
In 1610 the nobles of Sinzendorf were raised to baron, and in 1653 to Imperial Count. 1653 bought Rudolf von Sinzendorf from Ernstbrunn the castle county Rheineck am Rhein, thus his line was part of the Kuriatstimme the Westphalian Grafenbank in the Imperial Imperial Council and rose to the imperial high nobility. In the second half of the 17th century, Georg Ludwig Graf von Sinzendorf bought the county of Neuburg am Inn, which was lost in 1680 again.
1654 Count Georg Ludwig von Sinzendorf from the Fridau-Neuburger line was invested as hereditary treasurer of the Holy Roman Empire; in token of this office, he was allowed to add the imperial crown to his coat of arms. In 1677, as the owner of the fief of Thannhausen (Swabia), he became a member of the Swabian Imperial College, until 1708 when this fief was sold by his descendants to the Counts of Stadion.
The line Neuburg am Inn is extinct in 1767. The line Ernst Brunn divided into two; the senior line, raised in 1803 to princes of the Holy Roman Empire, included the dominions Ernst Brunn, Klement, Straussberg, Triebel, Castle Eichhorn (from 1707-1802), inter alia, in Austria, Bohemia and Moravia, and the castle county Winterrieden in Bavaria, which the family was given in compensation for the lost County Rheineck. With Prosper of Sinzendorf on Ernstbrunn (1751-1822), raised to the rank of sovereign imperial prince in 1803, but mediatized to Bavaria in 1806. With the death of Prince Prosper the family died in 1822 in the male line. It was followed by a protracted inheritance dispute that ended in 1828 when Prince Henry LXIV of Reuß-Köstritz took over the rule of Ernstbrunn, whose descendants still have it today.
The younger line also had properties in Austria and Bohemia, Planá (Tachov District), Kočov and so on.
Representatives of the noble family included:
Sinzendorf, die Grafen und Fürsten, Genealogie. In: Biographisches Lexikon des Kaiserthums Oesterreich. 35. Theil. Kaiserlich-königliche Hof- und Staatsdruckerei, Wien 1877, pg. 13–15.