The bass clarinet is a clarinet made by the same person who created the saxophone. It is an orchestral instrument, part of the low woodwind section, same as the bassoon. It uses a single reed and mouthpiece, along with a ligature, like the clarinet and saxophone. It comes in two types. The Eb bass clarinet and the C bass clarinet. The only difference, since both are in the key of Bb, is how low the instrument goes. The Eb bass clarinet's lowest note is the Eb nearly one octave lower than middle C on the piano. The C bass clarinet's lowest note is one whole step lower than an octave below middle C on the piano.

The Eb bass clarinet has one extra key that the Bb clarinet does not have, while the C bass clarinet has two extra keys. These keys are located where the right pinkie of a bass clarinet player would go.

The key closest to the bottom is the extra key on an Eb bass clarinet.