The acoustic bass guitar (also called ABG or acoustic bass) is a bass instrument with a hollow wooden body similar to, though usually somewhat larger than a steel-string acoustic guitar. Like the traditional electric bass guitar and the double bass, the acoustic bass guitar commonly has four strings, which are normally tuned E-A-D-G, an octave below the lowest four strings of the 6-string guitar, which is the same tuning pitch as an electric bass guitar. It could also be considered a mandobass, seeing as how both instruments are tuned exactly the same way, and produce exactly the same sound.

Because it can be difficult to hear an acoustic bass guitar without an amplifier, even in settings with other acoustic instruments, most acoustic basses have pickups, either magnetic or piezoelectric or both, so that they can be amplified with a bass amp.