OBJECTIVE The purpose of this study was to compare perinatal regionalization and neonatal mortality in Wales and Washington State. METHODS The 28 hospitals in Wales and the 80 hospitals in Washington State that offered maternity services and the 218,326 births that occurred in these hospitals in 1989 and 1990 were studied. Surveys were used to identify the neonatal technology and the referral policies of each hospital, and linked data from birth and death certificates were used to examine birthweight-specific neonatal mortality rates for all babies born in these hospitals. RESULTS Welsh district general hospitals (broadly equivalent to Level II perinatal centers in the United States) have more sophisticated neonatal technology than their Washington State counterparts and appear less likely to refer small or preterm babies to regional or subregional centers. Neonatal mortality rates were quite similar in the two settings. CONCLUSIONS Perinatal care in Wales appears to be less regionalized than in a similar region in the United States. The relative lack of perinatal regionalization in Wales may contribute to duplication and underutilization of expensive neonatal technologies. National health care systems do not, in and of themselves, lead to optimal regionalization of services.