A case of recurrent hydrops fetalis, diagnosed on second trimester's ultrasonography, has led to the diagnosis of sialic acid storage disease. No classic etiology was found after the first accident. The recurrence in subsequent pregnancy raised the possibility of a storage disease that was confirmed by amniocentesis. The diagnosis of Salla's disease was based on high levels of free sialic acid in amniotic fluid and fetal cells culture and by specific histologic features on fetopathologic examination. Diagnosis of inherited diseases is important because it implies a high risk of recurrence which makes mandatory genetic counseling and prenatal care in subsequent pregnancies.