Although bicuspid aortic valve is the most common congenital abnormality, it is perhaps erroneous to consider this disease one clinical entity. Rather, it may be useful to consider it a cluster of diseases incorporating different phenotypes, etiologies, and pathogenesis. Discussion of bicuspid aortic valve can be difficult because there is no clear consensus on a phenotypic description among authors, and many classification schemes have been proposed. The literature suggests that different phenotypes have different associations and clinical manifestations. In addition, recent studies suggest a genetic basis for the disease, yet few genes have so far been described. Furthermore, recent scientific literature has been focusing on the increased risk of aortic aneurysms, but the pathogenesis of bicuspid aortic valve aortopathy is still unclear. The aim of this paper is to review the current evidence about the unsolved issues around bicuspid aortic valve.