The efficacies of ultrasonic abdominal circumference (AC) and abdominal area (AA) measurements in the evaluation of intrauterine fetal growth were compared. The intraobserver random and technical errors were found to be significantly higher with AA measurements. The correlation with intrauterine fetal weight was observed to be better with AC as compared with AA measurements, the fetal weights being expressed as either linear regressions or multiple regressions involving the two parameters. Between 32 and 38 weeks, a single AC measurement detects 74 per cent of small-for-date fetuses, while a single AA measurement detects only 58 per cent of such fetuses. The false-positive rates were similar for the two parameters. It is concluded that AA measurements are no more useful than AC measurements in the routine assessment of intrauterine fetal growth.