Optical Coherence Tomography (OCT) is a novel, non invasive imaging method, which enables in vivo assessment of living tissues, providing near histological resolution images. The first description of its clinical introduction was in ophthalmology, which substantially changed our view of specific retinal diseases. OCT technology is slowly penetrating into other medical fields, supposedly opening new perspectives with the possibility of in vivo optical biopsy. The aim of this paper is to review the clinical use of OCT, with special emphasis on ophthalmology.