Amniotic fluid volume assessment using a semiquantitative four-quadrant technique, the amniotic fluid index, was evaluated in relationship to fetal heart rate (FHR) testing and perinatal morbidity in 330 high-risk pregnancies. An inverse relationship was found between the amniotic fluid index and nonreactive nonstress tests (NST), FHR decelerations, meconium staining, cesarean section for fetal distress, and low Apgar scores. More important, adverse perinatal outcome was significantly more frequent with diminished compared with normal amniotic fluid volume, even if the NST was reactive.