The relationship between complete absence of all components of the fetal biophysical profile score (biophysical profile score = 0) and adverse perinatal outcome was examined. Twenty-nine of 28,655 fetuses studied (0.092%) had a last biophysical profile score of 0; 48.3% of these perinates died (14 of 29 fetuses), the majority of whom (11 of 14) were stillborn, with death occurring as early as 30 minutes to as long as 11 days after the last test. Three asphyxia-related neonatal deaths occurred despite aggressive and immediate intervention. All survivors exhibited at least one of the five discrete markers used to assess perinatal morbidity. The positive predictive accuracy of a biophysical profile score of 0, with mortality and morbidity used as end points, was 100%. These data indicate the very abnormal fetal biophysical profile score to be a perinatal emergency.