Aplastic crisis in patients with sickle cell disease who develop a parvovirus infection may be associated with extensive bone marrow necrosis as well as acute selective erythroblastopenia. This illness may be manifested by pyrexia, lymphadenopathy, bone tenderness and significant hypoxemia with minimal roentgenographic findings in the lungs. It is uncertain whether the hypoxemia is caused by the effects of the viral infection on the lungs or is secondary to sickling of red blood cells in the pulmonary vasculature or both. The hypoxia may be sufficiently severe to require treatment with both oxygen and transfusion. The physical damage to the bone marrow associated with bone marrow necrosis may be more important than selective acute erythroblastopenia in inducing aplastic crisis in patients with sickle cell disorders. Studies of bone marrow biopsy specimens collected during parvovirus-associated aplastic crisis in patients with nonsickle cell hemolytic disorders would be helpful in determining the pathophysiology of parvovirus-associated disorders.