Currently, it is the standard of care to use the pp65 antigenemia assay to guide anti-cytomegalovirus therapy in hematopoietic stem cell transplant patients. Nevertheless, over the past two years at our institution, only approximately 10% of antigenemia-positive patients went on to develop overt CMV disease and only 22% of patients with documented clinical CMV disease had a positive antigenemia test in the two weeks prior to diagnosis (data on file).