OBJECTIVE To determine whether the middle cerebral to umbilical artery systolic/diastolic velocity waveform ratio (MC/UA) was a more sensitive indicator of fetal compromise than the non-stress test (NST). STUDY DESIGN An outcome study of high-risk patients undergoing NST testing and MC/UA studies within 10 days of delivery. Patients were divided into four groups based on their test results, and neonatal outcome parameters were compared. RESULTS There were significant differences between all four test result groups with respect to length of stay in the neonatal intensive care unit (NICU). Patients in whom both the NST and MC/UA ratio were normal had significantly lower utilization of Cesarean section for delivery, admission and length of stay in the NICU and occurrence of significant neonatal complications. Logistic regression analysis indicated that the combination of the NST and MC/UA ratio was an excellent predictor of perinatal outcome. CONCLUSIONS The MC/UA ratio improves the sensitivity for the prediction of poor perinatal outcome when it is combined with the NST.