Sickle cell disease (SCD) is a relatively rare blood disorder that is characterised by the presence of crescent-shaped — sickled — red blood cells in the bloodstream. These crescent-shaped cells are stiff and sticky and can block blood flow in the small blood vessels of the peripheral blood system, thus preventing the normal flow of nutrition and oxygen. SCD is inherited in an autosomal recessive manner. In this article, Trudie Young gives a comprehensive overview of this medical condition and its link to lower limb ulceration.