Few medical issues are more controversial than carotid endarterectomy. The subject has been featured in the general press and on prime-time television; dispute has been encouraged between surgeon and nonsurgeon, with "needless surgery" a refrain poorly concealed in the background. These debates usually have more passion than substance. What is painfully obvious to experts on stroke is that we still don't know which patients, with what lesions, detected by which tests, should be treated, and with what therapies. In the past decade, the epidemiologic and pathological aspects of carotid-artery disease have been better defined. Techniques for diagnosis have multiplied, creating . . .