The goal of the study was to assess the prognostic value of ultrasound finding of fetal cystic hygromas. Thirty cases of septated cystic hygromas were diagnosed at 10-15 weeks gestation by transabdominal ultrasound and followed through pregnancy. The rate of abnormal karyotype was found to be 61% and the global rate of unfavorable outcome, independently of karyotype result, as high as 96%. These data suggest that cautious genetic counselling should be offered when such cystic hygromas are noticed during the first 15 weeks of gestation, even with a normal karyotype.