The prediction of the fetus at higher risk is commonly attempted using laboratory tests. It is difficult to measure the precision of these tests and so a prospective survey has been performed comparing six such tests and the clinical assessment of fetal progress in the last weeks of pregnancy. The ultrasound assessment of the fetal bi parietal diameter, urinary oestrogens, plasma oestriol, human placental lactogen, the activities of heat stable alkaline phospha-tase and cystine amniopep[idase were investigated in 189 patients. No single test was significantly effective in the prediction of perinatal death, low Apgar score or weight retardation, even the most precise misclassifing approximately 25% of the cases. Combining the tests improved prediction significantly and weighting factors were constructed to predict the small-for-dates babies and those with low Apgar scores. It was concluded that, while these indi-ces were too cumbersome for regular use, such a grouping of tests may indicate what the dinician does when he weighs up many factors before making a decision about taking any action about induction of labour and further combinations should be sought.