Aim of the present Consensus Statement is to provide a comprehensive and up to-date document on the pathophysiology, atherogenicity and clinical significance of low density liproproteins (LDL) subclasses. We sub-divided our statement in 2 sections. section I discusses the pathophysiology, atherogenicity and measurement issues, while section II is focused on the effects of drug and lifestyle modifications. Suggestions for future research in the field are highlighted at the end of section II. Each section includes Conclusions.