The Atherosclerosis and Dysmetabolic Disorders Study Group, headed by Prof. Rodolfo Paoletti, decided in 1994 to compose a committee of experts to formulate a clear description of familial combined hyperlipoproteinemia (FCH), a disorder illustrated in the literature, but still unknown to most physicians in spite of its severity and relative diffusion. The Committee consists of experts from the Lipid Clinics of the Universities of Ancona, Bari, Bologna, Ferrara, Genoa, Milan, Naples, Padua, Palermo, Perugia, Rome, Sassari, Turin, Verona and Venice. It has held several meetings coordinated by the national secretary at the "Giancarlo Descovich" Atherosclerosis Centre of the University of Bologna. This paper summarizes its conclusions.