The creations of Zaj Quartet results from a common approach for the place of improvisation in jazz as live music. Improvisations by Zaj Quartet leads to a kind of spontaneous compositions, including in jazz music various references as : jazz, classic, traditional, contemporary musics, beyond the cleavages of style. But what really makes the musical vitality of Zaj Quartet is first of all how it keeps this first breath of all musics: improvisation. What emanates from Zaj Quartet's music is a kind of musical alchemy mixed with a sound creativity which also gives a good place to the harmony even to the melody.