Vitamin K antagonists are advised in pulmonary arterial hypertension patients despite a lack of safety data. We reviewed major bleeding in three classes of pulmonary hypertension patients, all receiving vitamin K antagonists. Bleeding event rates were 5.4 per 100 patient-years for patients with idiopathic pulmonary arterial hypertension, 19 per 100 patient-years for connective tissue disease related pulmonary arterial hypertension patients and 2.4 per 100 patient-years for chronic thromboembolic pulmonary hypertension patients. Life tables analysis showed that event-free survival was worse in patients with connective tissue disease related pulmonary hypertension than in patients with idiopathic pulmonary arterial hypertension (Wilcoxon=12.8; p<0.001), and patients with chronic thromboembolic pulmonary hypertension (Wilcoxon=23.2; p<0.001). Patients with idiopathic pulmonary arterial hypertension suffered more events than patients with chronic thromboembolic pulmonary hypertension (Wilcoxon=7.2; p<0.01). Major bleeding was independent of age, sex, target international normalised ratio (INR) range, documented INR, vitamin K antagonist type, or right atrial pressure, but was associated with use of prostacyclin analogues. Major bleeding risk during vitamin K antagonist therapy differs among groups of patients with pulmonary hypertension. Further research regarding optimal anticoagulant therapy is needed, as well as risk-benefit analyses for pulmonary hypertension patients with a higher bleeding propensity.