The Orchester Musikkollegium Winterthur is a symphony orchestra based in Winterthur, Switzerland. The oldest orchestra in Switzerland, it was founded in 1875 as the Stadtorchester Winterthur. The Musikkollegium itself as an organisation out of religious roots to that time was founded in 1629. The orchestra performs around 60 concerts a year, and in addition to orchestra concerts, performs in the pit at the Zurich Opera.
From 2002 to 2008, Jac van Steen was principal conductor of the orchestra. The orchestra and van Steen made several commercial recordings for the MDG label, including music of the composers of the Second Viennese School and of Frank Martin. In April 2008, the orchestra announced the appointment of Douglas Boyd as its next principal conductor, effective with the 2009-2010 season.
In the modern repertoire, the orchestra works often with Heinz Holliger, and in the baroque repertoire with Maurice Steger and Nicolas Kraemer.