Carbon nanotubes (CNT) are emblematic nanomaterials, presenting unique physico-chemical properties, such as mechanical, thermal, or electrical conductivity, that have led to a large number of actual applications and uses, as well as (future) developments in aerospace, automobiles, nanoelectronic, or nanomedicine. CNT are currently used in many devices (computers, aircraft airframe, and sporting goods such as tennis rackets, bicycles, golf irons) and have also emerged as efficient drug delivery carriers in the biomedical and drug delivery fields[1]. Because of these actual and future applications, there's an increasing concern regarding the consequences that could result from human exposure to CNT, particularly at the respiratory level, since it represents a major route of exposure to nanomaterials. This review will highlight the advancement in the actual knowledge on lung toxicities of CNT, and try to better understand the underlying biological mechanisms, as well as the importance of physico-chemical determinants directly related to CNT characteristics.