Fetal pleural effusions can be primary or secondary, with an estimated incidence of 1: 10.000-15.000 pregnancies. Pleural effusion may occur at any time during the neonatal period, at birth, or antenatally, diagnosed by ultrasound. The clinical course is unpredictable. Whereas smaller unilateral effusions might remain stable or even regress, this is rare in cases with larger collections. Precise diagnosis of the etiology is important for subsequent management. Herein we present a succesfully treated newborn with isolated congenital pleural effusion which was associated with supraventricular tachycardia.