We have experienced a case of neonatal Group B Coxsackie virus Type 5 (Coxsackie B5) infection (case 1) who died at the age of 4 days and a case of neonatal Coxsackie A Type unknown infection (case 2) who died at the age of 14 days.Case 1 revealed slight meningitis, pericarditis, hepatitis, atelectasis, bronchopneu-monia, splenic hemorrhage, outer adrenal cortical cyst and starry sky appearance of the thymus.Case 2 showed subarachnoid hemorrhage of the spinal cord, slight meningitis, mye-litis, carditis, bronchopneumonia, hepatitis, central necrosis of the splenic white pulp, infectious spleen, pancreatitis, outer adrenal cortical cyst and partial starry sky appear-ance of the thymus.Meningitis was mild in both cases, but carditis was severe in case 2. On the other hand starry sky appearance and involution of the thymus was severe in case 1. We have reported that starry sky appearance of the thymus is initial response to stress in human beings.If changes of the thymus are markers of the response to stress, it may be concluded that severe change of the heart in case 2 is not due to stress but to pathogenesis of the virus itself.