Genetic mutations in members of the transforming growth factor-beta receptor superfamily are associated with two diseases characterised by changes in the structure of the lung vasculature, pulmonary arterial hypertension and hereditary haemorrhagic telangiectasia. Pulmonary arterial hypertension is characterised by increased vessel muscularisation, sharply contrasting with the reduction in smooth muscle that occurs in hereditary haemorrhagic telangiectasia. Intriguingly, both pathologies can exist in some patients with combined disease. In this review, we discuss the contributions of convergent and divergent ligand response profiles and differing tissue expression patterns of the affected receptors to the pathologies of these diseases. We address the possible contribution of inflammation in disease progression and focus on potential emerging therapeutic targets.