Abstract Background Pulmonary arterial hypertension (PAH) in adult patients with congenital heart disease (CHD) is associated with increased morbidity and mortality. There is growing evidence that PAH drugs lead to improved hemodynamics, exercise capacity, quality of life and survival in patients with PAH. Purpose The aim of this systematic review and meta-analysis is to evaluate the effects of pulmonary hypertension (PH) medical therapy on the haemodynamic parameters as well as exercise capacity in adult patients with PAH-CHD. Methods PubMed and the Cochrane Library databases have been systematically searched. Meta-analysis was conducted using STATA and Review Manager. Results Fourteen studies including 575 patients were analyzed. Pulmonary haemodynamics improved in patients receiving PH-targeted therapy. The weighted mean reduction in mean pulmonary arterial pressure (mPAP) was -5.8mmHg (I2=0%, 95% CI [–7.55, –4.06], p<0.001).The weighted mean reduction in right atrial pressure (RAP) was -5.81mmHg (I2=0%, 95% CI [-7.55, - 4,07], p<0.001). The weighted mean reduction in pulmonary vascular resistance (PVR) was 358.5dynes/sec/cm-5 (I2 51%, 95% CI [-566.55, -150.46] and p<0.001). Cardiac index was increased by 0.61L/min/m2 (I2=6%, 95% CI [0.23,1.00], p=0.002). Six-minute walking distance increased by 47.26m, (I2=0%, CI [38.36, 56.16], p<0.001). Conclusions PH-targeted therapy improves pulmonary haemodynamics and exercise capacity in adult patients with PAH-CHD.