A pregnancy with placental sulfatase deficiency was suspected when a 31-year-old patient at 36 weeks of gestation was found to have extremely low urinary estriol excretion but an otherwise normal prenatal course. The maternal plasma level of estrogens was extremely low, whereas dehydroepiandrosterone sulfate (DHA-S) was normal. Following intravenous infusion of 100mg DHA-S, no rise in urinary or serum estrogens was noted. At 40 weeks of gestation, a male infant was delivered vaginally. In vitro incubation study confirmed the diagnosis of placental sulfatase deficiency. Arylsulfatase C activity was not demonstrated in sulfatase deficient placenta, whereas arylsulfatase C activity was detected in the cytoplasma of syncytiotrophoblast cells of all normal placentas, by light and electron microscopy.