Ultrasound and Doppler umbilical artery velocimetry have been used to diagnose the small-for-gestational-age (SGA) fetus. Both techniques are relatively inefficient for this diagnosis. The aim of the present study was to see whether their serial use improved diagnostic accuracy. Forty women with an ultrasound diagnosis of SGA within three weeks of delivery were studied with velocimetry, and the outcome was evaluated. Diagnostic accuracy was improved from 65% by ultrasonography alone to 92% by the addition of an abnormal umbilical artery waveform (P < .02). An abnormal waveform was associated with an adverse outcome in 62%, compared to 14% with normal velocimetry (P < .01). The majority of small fetuses have a normal outcome. The combination of ultrasonography and velocimetry improved diagnostic accuracy and identified those small fetuses truly at risk.