Randomized clinical trials have not provided unequivocal justification for the routine use of ultrasound in antenatal management. Nonetheless, routine ultrasonography is widely practiced in many places, there is no evidence to suggest it is biologically harmful, and its diagnostic capabilities are being increasingly documented. There are, however, no studies of the clinical, psychological or economic benefits of routine ultrasound in clinically low-risk patients who would not normally be scanned. To avoid continuing uncertainty about the risks and benefits of routine ultrasound, randomized trials should be conducted of future developments in technique and procedure in places where routine scanning is common. In places which have not adopted routine scanning randomized trials could still answer fundamental questions about routine use of the technique.