A retrospective analysis of the ultrasonic charts of 150 pregnancies with a birth weight below the tenth percentile is presented. In all cases the first scan was carried out before the 20th week of gestation to assess gestational age measuring crown to rump length or biparietal diameter (BPD). Subsequent scans every 4 weeks measured BPD or abdominal circumference. Birth weight was below the fifth percentile in 70 cases and between the fifth and tenth percentiles in 80 cases. A risk condition was found in 32.26%. The first observation of an abnormal parameter was widely spread throughout the latter half of the pregnancy. The management of IUGR included close observation and often required planned delivery. Cesarean section was required in 30.75% of the cases. Acute fetal distress has been the indication in 17.6% of cases and chronic fetal distress in 41.3%. Perinatal mortality was 6.66%. The need for criteria that will accurately detect the fetus most at risk from complications of IUGR is stressed.