Sammartini was a prolific composer, and his compositions include 3 operas, about 70 symphonies, ten concertos and some of the earliest chamber music known in the history of western music. As of 2004, approximately 450 known works have been composed by Sammartini, although a fair amount of his music has been lost, especially sacred and dramatic works. Some of it may have also been lost due to publishment under other names, especially that his brother, Giuseppe. His earliest music was for liturgical use.