This study revealed that the ripening stage affects significantly the yield and the composition of the examined Tunisian citrus. Immature stage offered the maximum yield for lemon while semimature fruit was the best ripening stage for mandarin and orange maltaise. In the case of bitter orange, maturity was the best stage. The oils chemical compositions and the antibacterial activity changed during ripening, and the maximum levels of the most abundant volatile compounds identified were dependent on maturity stage. For the four citrus, the highest limonene level was reached already at immature stage which suggests that at least in the case of lemon and for economic purposes, fruits could be harvested at immaturity in order to obtain essential oil with high yield and limonene content.