Teisnach (Northern Bavarian: Deisna) is a larger municipality in the district of Regen in Bavaria in Germany.

By the late 19th century, the once small village developed into an industrial hub within the region when a paper factory was opened on the shore of the Schwarzer Regen.

In 1969, the Rohde & Schwarz company opened a manufacturing plant in Teisnach which expanded into one of the largest employees in the region, employing nearly 2000 workers.

Since 2009, Teisnach hosts a branch of the Technische Hochschule Deggendorf, where the world's largest machine for producing space telescope mirrors is situated.

His predecessor, Rita Röhrl who was mayor since 1990, left office after she was elected head of the Regen district.