A patient with sickle cell anemia was hospitalized because of an acute erythropoietic aplastic crisis. 111In chloride bone marrow scintigraphy performed during the aplastic crisis showed markedly impaired uptake of the radionuclide and simultaneous 59Fe clearance T1/2 studies were prolonged (420.9 min). Following recovery from the aplastic crisis 111In scintigraphy revealed an expanded marrow and the radioiron clearance T1/2 was accelerated (20.9 min). The clinical course, hemograms and bone marrow aspirations correlated with marrow scintigraphy. 111In appears to be a valuable bone marrow scanning agent for assessing the presence of intramedulllary erythropoietic activity.