The effectiveness of three methods (Campbell and Wilkin,6 Warsof,3 Warsof et al4) for estimating fetal weight from measurements of the abdominal circumference (AC) and biparietal diameter (BPD) has been evaluated in 125 patients studied with dynamic image ultrasound. Investigations of the population as a whole indicated that the Campbell-Wilkin and Warsof methods systematically overestimated the weight (mean deviation: 5.3% and 1.6%, respectively), while the method of Warsof et al gave systematic underestimations (mean deviation: – 3.2%). The variability of the two Warsof methods was similar (SD: 8.8% and 8.4%) and significantly lower than that seen with the Campbell-Wilkin method (SD: 13.9%). When separate weight subclasses (500 gm to 4500 gm) were examined, the mean deviations and their variability were significantly lower with the two Warsof methods. The method of Warsof3 showed the most consistency among the weight subclasses. These results indicate that of these three methods, the best estimates of fetal weight are provided by the Warsof3 procedure.