Fetal abdominal circumference (AC), abdominal area (AA), antero-posterior diameter (APD), and transverse diameter (TD) were measured by real-time ultrasonic B-mode scan technique in 190 cases of 31 to 42 weeks of gestation within 48 hr prior to the birth. The AC and AA were calculated by the microcomputer (NEC PC-6001) with the use of traced figure of fetal abdomen. APD+TD, APD×TD, AC, and AA showed the significant correlations with the birth weight, and the correlation coefficients were 0.92, 0.92, 0.91, and 0.91 respectively. There was the tendency to underestimate fetal weight in the cases which showed anterior or posterior location of fetal spine if APD and TD were utilized in fetal weight estimation. Small-for-dates and large-for-dates infants were predicted with use of the growth curve of APD+TD which was obtained from 432 determinations of fetal body in the cases of 19 to 42 weeks of gestation. Sensitivity was higher in the use of mean±1 S.D. curves than the mean±3/2 S.D. curves in spite of small change of the specificity.