We read with great attention the article by Liu et al in a recent issue of CHEST (May 2016) regarding ultrasound diagnostic criteria of transient tachypnea of the neonate (TTN). It is an unmasked, retrospective series by a single ultrasonographer that reaches conclusions different from what had been previously described.,,, Liu et al show that no ultrasound picture is unique to TTN and basically not distiguishable from respiratory distress syndrome (RDS). They also allude to a different ultrasound appearance between the acute vs the convalescent patient with TTN. Although some degree of overlapping is acknowledged, TTN and RDS are different diseases. The former results from delayed clearing of lung fluid, particularly frequent in late preterm infants. The latter is due to deficient surfactant production, a common feature of significant prematurity.