Fractional ablative lasers have recently proven to be an effective modality for improving the clinical appearance and minimizing the morbidity associated with restrictivetype scars. Their tolerable safety profile on nonfacial sites and darker Fitzpatrick skin types provides an advantage over its fully ablative counterpart in treating facial rhytides, photodamaged skin, and acne scars. However, despite its increasing usage in clinical practice, the mechanism behind the observed clinical benefit remains complex and has yet to be fully elucidated. This paper reviews the work on the histological mechanism of action of ablative fractional lasers, and the molecular changes that occur posttreatment on restrictive scars, with an emphasis on mature burn and postsurgical scars. As the majority of research has been on the carbon dioxide laser, a natural focus on this wavelength is presented. Semin Cutan Med Surg 34:7-12 © 2015 Frontline Medical Communications