This study evaluates the impact of regional differences in access to intensive neonatal care on neonatal survival in geographically defined populations of 4,692 low birthweight births in Norway 1979-81. For infants weighting 1,250 to 2,499 g our results are consistent with the existence of a dose-response association between neonatal survival and the level of immediate access to intensive neonatal care. Although not statistically significant, there was a clear gradient in the risk of mortality within 24 hours. A similar pattern of survival could not be consistently demonstrated for infants weighing less than 1,250 g.