Abstract Background: Pulmonary hypertension (PH), group III of the international aetiological classification, is a frequent and severe complication of interstitial lung diseases (ILDs), espe-cially idiopathic pulmonary fibrosis (IPF), Phosphodiesterase 5 inhibitor (Sildenafil) appears induce vasodilatation in well-ven-tilated lung tissue. Such vasodilatation could gas exchange in patients with idiopathic pulmonary fibrosis. Aim of Study: To assess the effect of phosphodiesterase 5 inhibitors (sildenafil) on pulmonary hypertension in patient with IPF after 3 months of treatment. Patients and Methods: Fifty patients with pulmonary hy pertension secondary to idiopathic pulmonary fibrosis, divided into two groups: The first group (30 patients) received phos phodiesterase 5 inhibitors; the second group (20 patients) didn' receive phosphodiesterase 5 inhibitors; all the patients had follow up visit after 3 months with assessment of high resolu tion CT scan & transthoracic echocardiography. Results: As regarding the class of dyspnea, there was sta tistically significant difference between the two groups with p-value (<0.001) favoring the treatment group. As regarding 6MWD and the change in PO2, there was statistically signifi cant difference with p-value (<0.001) favouring the treatmen group. Also, there was statistically significant difference p-val ue (0.001) favouring the treatment group regarding the change in FVC%. Conclusion: This study supports that the patients who re ceived sidinafil had a better outcome as regards class of dysp nea, 6 MWD, PO2, FVC% and PASP.