Committee on Vascular Lesions had compiled much of what is known about the composition and structure of human atherosclerotic lesions and about arterial sites at which they develop. 1–3 The statements had concluded by recommending a numerical classification of histologically defined lesion types. The recommendation was thought to be timely and appropriate. Several autopsy studies in which state-of-the-art histological methods were used had just thrown new light on the compositions of lesions and on the diversity of mechanisms whereby they developed. After reviewing the new data, the Committee felt obligated to recommend use of a standard numerical nomenclature of precisely defined lesion types to replace a variety of duplicate and vague terms. The provision of an up-to-date histological classification of lesions was perceived as a priority, not least because of the urgent need for histological “templates” for images of lesions that were being obtained with a variety of invasive and noninvasive techniques that had become available in clinical practice.