Therapy with sildenafil has been shown to decrease pulmonary vascular resistance and may improve functional status in patients with interstitial pneumonia (IP) and pulmonary hypertension (PH). Patients with IP and PH defined by a mean pulmonary artery pressure (MPAP) of > or = 25mm Hg on right-heart catheterization were followed up in an open-label study of sildenafil. A multilateral evaluation was conducted before, and after 3 months of therapy. We studied 11 patients [8 men and 3 women, mean age 66.5] 6 of whom had IPF (1 with usual interstitial pneumonia {UIP}), 2 with IIP, and 3 with collagen-vascular disease interstitial pneumonia (CVD-IP). The mean modified Medical Research Council (MRC) score was 3.0 +/- 0.89, baseline dyspnea index (BDI) score was 4.5 +/- 1.9, % VC was 58.7 +/- 15.6%, percentage of carbon monoxide diffusing capacity (%DLco) was 20.0 +/- 10.9%, six-minute walk distance (6MWD) was 269.8 +/- 105.5m, shuttle walking test (SWT) was 179.1 +/- 99.7m, St. George Respiratory Questionnaire (SGRQ) was 70.9 +/- 15.6, mean pulmonary artery pressure (MPAP) was 33.8 +/- 7.61mm Hg, and pulmonary vascular resistance index (PVRI) was 658.9 +/- 236.1 dynes x s x cm(-5) x m2. After 3 months of therapy, improvements in BDI (< or = -1), 6MWD (> or = 20%), SWT (> or = 20%), and SGRQ (< or = -7) were observed in 4, 2, 3, and 6 patients, respectively. Improvements in MPAP (< or = - 20%) and PVRI (< or = -20%) were observed in 2 and 3 patients, respectively. No parameter showed statistically significant differences. We conclude that sildenafil may improve dyspnea, exercise tolerance and health-related quality of life (QOL) in some IP patients with PH.