Directional coronary atherectomy (DCA) was introduced as a new percutaneous revascularization modality in 1990, and was initially applied to large vessels without tortuosity or calcification, with overall results including a 95% procedural success, 94% clinical success and 4.6% major complications (urgent bypass surgery in 3.8%, Q wave myocardial infarction in 1.7%, and hospital mortality in 0.3% of patients). In addition to its established efficacy for eccentric lesions, newer applications emerged such as treatment of saphenous vein grafts, thrombus-associated lesions, aorto-ostial lesions, failed or suboptional coronary angioplasty results, bifurcation lesions and use as a part of multi-vessel intervention. Comparative studies with coronary angioplasty such as CAVEAT I and II and CCAT showed better success rates with DCA vs coronary angioplasty, but failed to demonstrate benefit in restenosis rates. OARS and BOAT studies helped define optimal atherectomy techniques, which led to better acute angiographic results and to the "debulking plus stenting" concept. A spin-off of those clinical applications has been the opportunity to study the histology of tissue excised by DCA in vivo in different clinical settings. Such studies, investigating plaque ulceration, thrombosis and inflammation are reviewed, with special emphasis on new insights into unstable angina; the future of atherectomy research is also outlined with a categorization of various possible protocols to be applied utilizing coronary atherectomy specimens from live patients.