A Chemnitzer concertina is a musical instrument of the hand-held bellows-driven free-reed category, sometimes called squeezeboxes.

It's essentially a bigger version of the Anglo Concertina that sounds more akin to an Accordion due to having Multiple Ranks of Reeds.

It is roughly square in cross-section, with the keyboards consisting of cylindrical buttons on each end arranged in curving rows.

Internal construction is different from other concertinas in that the action more closely resembles that of an accordion, and that the reeds are of steel (rather than brass) and are often fixed in groups of twenty or more to long zinc or aluminum plates, rather than to individual frames.

Especially in English-speaking countries, the term Chemnitzer is frequently applied to any of the square German concertinas that are not bandonions.

Albert G. Nechanicky (1909-1986) invented the 130-key Chemnitzer concertina which is fully chromatic, allowing it to play in every key.

"Whoopee John" Wilfahrt and Walter "Li'l Wally" Jagiello were two prominent examples of polka musicians playing Chemnitzer concertinas.