To determine whether hormone analysis of amniotic fluid could be used for accurate determination of fetal sex, we measured testosterone(T) and follicle-stimulating hormone in 19 amniotic fluid samples. The mean T in amniotic fluid of 8 women earring male fetuses was 310 pg. per milliliter and of 11 women earring female fetuses was 150 pg. per milliliter (P<0.05${ast}$). The mean amniotic fluid FSH of 1.16 mI.U. per milliliter for 7 women with male fetuses was over trifold lower than that for subjects with female fetuses. The mean amniotic fluid FSH of female fetuses was 3.85 mI.U. per milliliter (P<0.01${ast}$) Measurement of T & FSH in amniotic fluid may be an adjunct method for fetal sex determination.