Systemic sclerosis (SSc) is a heterogeneous disorder characterised by dysfunction of the endothelium and dysregulation of fibroblasts, resulting in excessive production of collagen, and abnormalities of the immune system. Progressive fibrosis of the skin and internal organs is a pathologic hallmark of the disease, resulting in major organ damage and failure. Pulmonary hypertension (PH) is frequent in patients with SSc and, pulmonary arterial hypertension (PAH) represents one of the main causes of death. PH is not a specific disease, but a haemodynamic condition characterized by a mean pulmonary pressure ≥25mmHg. In SSc, because of the great variability in clinical manifestation, it is possible to identify pulmonary hypertension due to left heart disease, PH due to respiratory disease or pulmonary arterial hypertension. The knowledge of PH and the right diagnosis are crucial to assess the most appropriate therapeutic strategy. In this article, the new classification criteria of PH have been examined taking into account the SSc clinical evolution and focusing on the different underlying pathogenetic mechanisms.