It has been 100 years since Herrick published the first medical case report of sickle cell disease. In 1949, Pauling discovered hemoglobin S (HbS). As early as the 1960-70s, emerged a coherent detailed molecular-level description of pathophysiology of sickle disease. It involved polymerization of deoxyhemoglobin S with formation of long fibers inside red blood cells (RBC) causing a distorted sickle shape and shortened lifespan. These changes constitute the basic disease process and account for hemolytic anemia and for obstructive events underlying vasoocclusive crises (VOC). However, they do not explain the mechanisms that trigger VOC. The purpose of this review is to present recent data on dehydration of sickle cell RBC, abnormalities in RBC adhesion to the vascular endothelium, the role of inflammatory events and of activation of all cells in the vessel, and abnormalities of vascular tone and carbon monoxide metabolism. These data provide new insight into the pathophysiology of the first molecular disease.