We are reporting the results of a 21-month study during which 653 couples were seen in consultation at the prenatal diagnostic center of the University Hospital in Amiens, referred by their physician. 171 patients presented a theoretical term under 11 weeks of amenorrhea, for whom the choice between chorionic villi biopsy or amniotic fluid tap was possible. The different situations and results are compared for each method. The rate of fetal death was 5.4 per cent for chorionic villi biopsy and 1.5 per cent for amniotic fluid tap.