Abstract Background: To investigate plasma Connective Tissue Growth Factor (CTGF) levels in Pulmonary Arterial Hyper-tension (PAH) associated with Congenital Heart Disease (PAH-CHD) in children and the relationships of CTGF with hemodynamic parameters. Plasma CTGF levels were calculated in 30 children with PAH-CHD and 30 health volunteers, using the subtraction method. Aim of Study: To assess plasma Connective Tissue Growth Factor (CTGF) levels in children with CHD and study its role in assessment of PAH that can be promising diagnostic and prognostic biomarkers for PAH in children with CHD. Patients and Methods: Our study was conducted in Pedi-atric Cardiology Clinic and Cardiology Catheter Laboratory of Ain Shams University Pediatric Hospital, in the period from Jan. 2019 to May 2020, including 30 patient and 30 healthy controls of matched age and sex. Results: The patients with PAH, 17 were acyanotic and 13 were cyanotic. The health control group and patient groups did not differ significantly in terms of age, gender and BSA (p>0.05). Height, weight and BMI were significantly lower in PAH-CHD group compared with the HCG (p < 0.05), while no difference was found between PAH-CHD group (p>0.05). In addition, CTGF levels were higher in PAH-CHD group than health control group. Depicts that, PAH-CHD group had higher PASP, PADP, RVSP, mPAP, Qp, Rp and Rp/Rs (p < 0.01). Conclusion: Plasma CTGF levels could be a promising diagnostic biomarker for PAH-CHD in children.