Steroid hormone determinations have been performed in amniotic fluid obtained by amniocentesis in 16 to 20 weeks of pregnancy utilizing our radioimmunological methods. Sporadic estimations reported in the literature were completed with our results of dehydroepiandrosterone (D) and dehydroepiandrosterone sulphate (DS) measurements obtained in relatively great number of cases. The observations allowed the early diagnosis of placental sulphatase deficiency. Study of this enzymopathy suggested that, in addition to oestrogens and progesterone, D and DS may have per se biological-hormonal effects for maturation processes in the intrauterine life. Furthermore, a hypothesis has been outlined for prenatal differential diagnostics of the congenital adrenal hyperplasia due to 3 beta-hydroxysteroid dehydrogenase deficiency.