A study was undertaken to assess the value of symphysis-fundus measurement as a screening procedure for intrauterine growth retardation. The reproducibility of this measurement was investigated in two groups of six patients, each measured six times by six different observers. The intraobserver coefficient of variation was 4.6% and the interobserver coefficient of variation 6.4%. There was no evidence that experience aided consistency. A chart of symphysis-fundus measurements derived from Cardiff data was found to be similar to others previously published, and one measurement below the 10th centile identified 64% of pregnancies in which the eventual birth weight was below the 10th centile for gestational age. Symphysis-fundus measurement is a useful screening test; one chart could be used for any Caucasian population and should be incorporated into the maternity services "co-operation card."