In the United States, The concept of designation for hospital facilities that care for newborn infants according to the level of complexity of care provided was first proposed in 1976. The extent of perinatal health care regionalization varies widely from one area to the other. facilities that provide hospital care for newborn are classified into three categories on the basis of functional capabilities; level I-primary or basic care, level II-secondary or specialty care, level III-tertially or subspecialty care. These facilities should be organized within a regionalized system of perinatal care. The transport system of newborn infants should be organized for referral of high risk newborn to centers with the personnel and resources needed for their degree of risk and severity of illness. In Korea, The korean society of neonatology was established and articulated in the 1994. During the past decade, the number of neonatologist has increased and neonatal intensive care units have proliferated in Korea. However, no standard definitions exist for the graded levels of complexity of care that neonatal intensive care units provide and no uniform guideline or recommendation for regionalization and referral system of high risk neonate have been established. With the rapid changing neonatal care system in Korea, the optimal neonatal care demands regionalization of care in utilization of manpower resources and in efficient use of advanced technology and facility.