The vibraphone, sometimes called the vibraharp or simply the vibes, is a musical instrument in the percussion family.

It is similar in appearance to the xylophone, although the vibraphone uses metal bars instead of the wooden bars on the xylophone. The standard modern instrument has a range of three octaves, from the F below middle C. Larger four octave models from the C below middle C are also becoming more common. The vibraphone is commonly played with cord or yarn mallets.Below each bar is a resonator, a resonant metal tube, with a metal disc of a slightly smaller diameter located at the top. The discs in each tube are connected via a rod which can be made to rotate with an electric motor. When the motor is on and a note is struck, the notes acquire a tremolo sound as the resonators are covered and uncovered by the rotating discs. The player can vary the speed of the tremolo. At slower speeds, the effect sounds more like a "wah-wah-wah." At faster speeds, the tremolo is more pronounced. With the motor switched off the vibraphone has a mellow, bell-like sound.

While the instrument's name comes from "vibrato", this is actually a misnomer, since the effect is actually tremolo, not vibrato (vibrato being a modulation in pitch, not amplitude). In any case, the tremolo sound is now perceived as dated, and many modern vibraphonists eschew the effect altogether.

The vibraphone also has a sustain pedal similar to that used on a piano. When the pedal is up, the bars are all damped and the sound of each bar is quite short; with the pedal down, they will sound for several seconds, so frequent rapid pedalling is common when playing a vibraphone.

The vibraphone was invented in the United States in 1921. It has a long history as a jazz instrument. However, the vibraphone has since been used in many other musical idioms, including popular music.

For a list of famous players, see vibraphonist.

As with the xylophone, early vibraphonists such as Lionel Hampton and Milt Jackson used two mallets to play the instrument. The instrument was primarily featured as solo instrument and contributed little to harmonic accompaniment. Modern vibraphonists such as Bobby Hutcherson, Gary Burton, Mike Mainieri, Matthias Lupri, Victor Feldman, Jerry Tachoir, Joe Locke and Dave Samuels, among others, use four mallets and the instrument has joined the modern jazz rhythm section as an accompaniment instrument. Often the vibes can substitute for a guitarist or pianist in this respect. The most common four-mallet grip used on the vibraphone is the Burton Grip named after Gary Burton. Five and six mallet grips are possible, but not as common, because using more mallets tends to adversely impact the player's ability to easily play melodic lines as well as the player's control of mallet position (making changes in chord voicing increasingly difficult).

Phrasing is a constant consideration for the player due to the mechanics of the instrument. Vibraphone bars have an extremely long sustain time, often rivaling that of the electric guitar or piano. Unlike the piano, the vibraphone only allows for one sustain and dampening system: the sustain pedal and single dampening bar. With the pedal up, the notes played have an extremely staccato sound. Legato playing requires that the pedal be depressed, however this can lead to the notes bleeding together. To promote clarity in legato phrasing and prevent the notes of a melody from bleeding together, modern vibists employ the technique of mallet dampening. To do this, the vibist holds the pedal down and dampens the previous note in a melody with the head of the mallet when playing the subsequent note. This also allows the player to let a chord ring out while playing a melody line above it. This is another technical innovation introduced by Gary Burton.

One experimental technique is a note bend effect by sliding a mallet from the node (the portion of the bar through which the string passes) to the middle of the bar. While it does not actually bend the pitch, it does have the effect of filtering out the overtones. Another is using the bows of stringed instruments (such as a double bass bow) as an alternative way to cause the bars to vibrate.

Mike Mainieri invented the first pickup system in 1964 for amplifying the vibraphone by gluing "Hot Dot" pickups to the nodal point of each bar. In the 1970s, Mainieri introduced the first monaural MIDI vibraphone, and in the 1980s developed a polyphonic system that could trigger any synthesizer with a MIDI input. Since then other vibists have also experimented with incorporating electronics to the instrument. Some third-party companies market kits to add pickups to the bars, allowing electronic amplification and MIDI control. The "MIDIfication" feature was only available for 3-octave vibraphones and was discontinued in 2005 for an unknown reason, possibly slow sales and/or high production costs.