The histological characterization of the fibroatheromatous plaques and their histogenesis are still to be defined. Factors responsible for the evolution of intimal components and the mechanisms and stages of fibroatheromatous plaque formation are still largely obscure. Focusing on symptomatic plaques, the aim of this study is to determine whether plaque heterogeneity is the result of a haphazard clustering of various components or an organized pattern in response to risk factors. To this end, 180 carotid plaques from patients affected by transient ischemic attacks (TIA) or by stroke, with angiographic stenosis greater than 50%, were studied after endoarterectomy. Clinical and morphological data were collected by means of a pre-defined protocol, quantified and correlated, by using the discriminant analysis, with age, sex, hypertension, diabetes, hypercholesterolemia and smoking habit. Our results show that the relationships between plaque components are non-random and consistent with the knowledge derived from studies on human and experimental plaques. Moreover, some plaque patterns can be significantly correlated with single risk factors. The fibrous plaque was correlated with aging and diabetes; the granulomatous plaque, rich in giant cells, with the female sex and hypertension; the xanthomatous plaque, rich in foam cells and with extensive alcianophilia, with hypercholesterolemia. In the smokers, finally, the plaques were frequently complicated by mural thrombosis.