Fibrosing mediastinitis is a rare disease, mostly associated with previous granulomatous diseases, such as histoplasmosis, tuberculosis, or sarcoidosis. We present a case of 42-year-old woman with sarcoidosis, who had developed fibrosing mediastinitis and pulmonary hypertension. Contrast-enhanced computer tomography showed abnormal, bilateral, solid tissues surrounding the hila and mediastinum. Magnetic resonance imaging showed: abnormal, intermediate signal tissue in the mediastinum, surrounding hila, narrowing both lower lobe arteries and both lobe bronchi, left upper lobe atelectasis, and contrast enhancement of mediastinal infiltration. The patient was treated with steroids for 14 months (initial dose of prednisone was 1 mg/kg/day, then tapered) with clinical and radiological improvement. We reviewed the literature concerning fibrosing mediastinitis. The various causes of that disorder, the radiological manifestation, and possible treatment modalities are discussed. The causes of pulmonary hypertension in our patient are another aspect of the article. It could be associated with both the fibrosing mediastinitis and the sarcoidosis.