Concentus Musicus Wien (CMW) is an Austrian baroque music ensemble based in Vienna. The CMW is recognised as being a progenitor of the period-instrument performance movement.

Nikolaus Harnoncourt and Alice Harnoncourt co-founded the CMW in 1953, along with several musicians from the Vienna Symphony Orchestra. The CMW did research and rehearsal for 4 years before their first official concert, although the ensemble did make its 'unofficial' debut at the Konzerthaus, Vienna in 1954 in a production of Claudio Monteverdi's Orfeo. The CMW's first public concert was in May 1957 at the Schwarzenberg Palace in Vienna. The CMW gave a regular concert series at the Schwarzenberg Palace from 1958 to 1962. The CMW made its formal debut in the Mozart-Saal of the Vienna Konzerthaus in February 1962, and performed concerts regularly there until 1971. The CMW performed its first opera production at the 1971 Wiener Festwochen in Monteverdi's Il ritorno d'Ulisse in patria. The CMW's first concert at the Musikverein, Vienna, was in 1973. The orchestra has continued to perform regularly at the Musikverein since then. Nikolaus Harnoncourt directed the ensemble from the cello until 1987, and has continued to lead the CMW as its conductor and artistic director.