Splenic function was evaluated after subcutaneous epinephrine injection (0.5 mg/m2) in 15 bone marrow transplant (BMT) recipients, 10 healthy volunteers and 5 healthy asplenic men. Healthy volunteers and BMT recipients with minor primary induction chemotherapy (mRx) showed similar rise in platelet (plt) and neutrophil granulocyte (PMN) counts and similar contraction of spleen. Patients with intensive primary induction chemotherapy (MRx), however, had significantly smaller spleens and spleen contraction (p less than 0.02) and no plt increase (p less than 0.05) when compared with healthy volunteers. 2 patients with MRx even exhibited a decrement of plt count after epinephrine, similar to that observed in all 5 healthy asplenic subjects tested. Our results suggest that mRx and conditioning for BMT including total body irradiation (TBI) does not alter the splenic function, but that the combination of MRx and conditioning regimen including TBI may cause functional hyposplenism, sensitively revealed by reduction in plt count after epinephrine stimulation.