List of musical instruments by Hornbostel–Sachs number: 321.31

This is a list of instruments by Hornbostel–Sachs number, covering those instruments that are classified under 321.31 under that system. These instruments are also known as spike lutes. These instruments are made of a resonator and string bearer that are physically united, with strings in parallel to the sound table and a handle which is also the string bearer and which passes diametrically through the resonator. The shape of the resonator divides the instrument into one of three subcategories: spike bowl lutes, spike box lutes and spike tube lutes.

The spike in the name spike lute refers to the fact that the handle passes through the resonator, often forming a spike after it emerges from it. In instruments like the Chinese erhu, the spike is vestigial, but in many instruments, like the rebab, it acts as support during performances.