Although much has been written regarding regionalization of obstetric services and inferences made about centralization of labor and delivery, little data exist that specifically address the volume-outcome relationship for obstetrics. The purpose of this study was to determine the relationship between physician volume and perinatal outcome as measured by neonatal and perinatal mortality. A sample of 210,547 births to Missouri residents from 1984 to 1987 was studied using multivariate logistic regression with perinatal death and neonatal death as outcomes. No relationship was found between physician volume and outcome.