Oxygen transport and delivery in sickle cell anemia are discussed in terms of hemodynamics and blood oxygen affinity. The current concepts of the regulation of the hematocrit value by the oxygen pressure on the venous side of the renal capillary are reviewed, and the concept of "anemia" redefined. The marked right shift in the oxygen dissociation curve of sickle cell anemia blood is analyzed in terms of the sickling process, the hemolytic anemia, and increase in 2,3-diphosphoglycerate. The clinical implications of this right shift in perpetuating sickling are discussed in the light of its possible correction by treatment with sodium cyanate.