Congenital diaphragmatic hernia (CDH) is attributed to severe pulmonary hypoplasia and pulmonary hypertension (PH). PH is characterized by structural changes resulting in vascular remodeling. Serotonin, a potent vasoconstrictor, plays a central role in the development of PH. It exerts its constricting effects on the vessels via Serotonin receptor 2A (5-HT2A) and induces pulmonary smooth muscle cell proliferation via the serotonin transporter (5-HTT). This study was designed to investigate expressions of 5-HT2A and 5-HTT in the pulmonary vasculature of rats with nitrofen-induced CDH.