A gas chromatographic procedure for the quantitation of neutral steroid sulphates in maternal urine and its application to a suspected case of placental sulphatase deficiency is described. Low levels of oestriol coincident with elevated 16-hydroxylated metabolites of dehydroepiandrosterone in the maternal urine are shown to occur in this particular condition, and thus provide a convenient differentiation from fetal adrenal hypoplasia before birth.