A case of non-immunitary hydrops fetalis, following supraventricular tachycardia, in a fetus of 29 weeks of a 28-year-old woman at the first pregnancy, who evolved with systemic hypertension and amniorrhexis, being submitted to cesarean deliver. The child needed bilateral thoracic drainage and oro-tracheal intubation for treatment of respiratory failure. Treated with digoxin and diuretic, the newborn went home at the 56th day of life. The authors emphasize the importance of the intrauterine diagnosis of the arrhythmia for the success of the treatment.