Objective Bartter syndrome is a severe inherited tubulopathy characterized by postnatal salt wasting, severe polyuria, dehydration, failure to thrive and secondary hyperaldosteronism. Prenatally, the disease is usually discovered following the onset of severe polyhydramnios in the second trimester. We studied amniotic fluid aldosterone concentration in Bartter syndrome and in controls. Methods Amniotic fluid aldosterone was assayed by radioimmunoassay. We undertook a retrospective case‐control study based on 36 cases of prenatally suspected and postnatally confirmed Bartter syndrome (22 with identified mutations): and 72 gestational age matched controls presenting with polyhydramnios and 72 without polyhydramnios. Amniotic fluid aldosterone was compared between the three groups. Results The median amniotic fluid aldosterone concentration in the Bartter syndrome group (90 pg/mL) was not different from that in the controls with polyhydramnios (90 pg/mL, P = 0.33) or without polyhydramnios (87 pg/mL, P = 0.41). Conclusion Amniotic fluid aldosterone assay cannot be used for prenatal diagnosis of Bartter syndrome. © 2015 John Wiley & Sons, Ltd. What's already known about this topic? Antenatal Bartter syndrome is a tubulopathy becoming apparent during pregnancy by polyhydramnios. An index based on amniotic fluid alpha‐fetoprotein and total protein is suggestive of Bartter syndrome. After birth, salt loss causes secondary hyperaldosteronism. What does this study add? In a series of 36 Bartter syndrome cases, we observed that assessment of amniotic fluid aldosterone did not contribute to the diagnosis of Bartter syndrome.