In a prospective blind study, 133 fetuses suspected of being small for gestational age (SGA), defined as an estimated fetal weight less than the 10th centile for gestation, were monitored by weekly biophysical profile assessment. Perinatal outcome was assessed by umbilical venous blood pH estimation and compared with the profile score determined within seven days of delivery. The positive and negative predictive values of the full biophysical profile score were not significantly better than combinations of two or three of the individual components in this group of fetuses. The use of amniotic fluid volume, non-stress testing and either fetal movement or breathing offers an acceptable alternative to full biophysical profile assessment in the fetus suspected of being small for gestation.