Background: Hereditary haemorrhagic telangiectasia (HHT) is a rare vascular dysplasia resulting in visceral arteriovenous malformations and smaller mucocutaneous telangiectasia. Most patients experience recurrent nosebleeds and become anaemic without iron supplementation. However, thousands may require anticoagulation for conditions such as venous thromboembolismand/or atrial fibrillation. Over decades,tolerance data has been publishedfor almost 200HHT-affected usersof warfarinand heparins, but there are no publisheddata forthe newer direct oralanticoagulants(DOACs)in HHT. Methods: To provide such data, aretrospective audit was conducted across the eight HHT centres of the European Reference Network for Rare Vascular Disorders (VASCERN),in Denmark, France, Germany, Italy, Netherlands and UK. Results: Although HHT Centreshad not specifically recommended the use of DOACs, 32treatment episodes had been initiated by other cliniciansin 28patients reviewed at the centres, at median age 65years(range 30-84). Indications were for atrial fibrillation (16 treatment episodes) and venous thromboembolism (16 episodes).The 32 treatment episodes used Apixaban (n=15), Rivaroxaban (n=14), and Dabigatran (n=3). HHT nosebleeds increased in severity in 24/32 treatment episodes (75%), leading to treatment discontinuation in 11 (34.4%). Treatment discontinuation was required for 4/15(26.7%) Apixabanepisodes and 7/14 (50%)Rivaroxaban episodes.By a 4 point scale of increasing severity,there was a trend for Rivaroxaban to be associated with a greaterbleeding riskboth including and excluding patients who had used more than one agent (age-adjusted coefficients 0.61 (95% confidence intervals 0.11, 1.20) and 0.74 (95% confidence intervals 0.12, 1.36) respectively. Associationswere maintained after adjustment for genderand treatment indication. Extreme haemorrhagic responses, worse thananything experienced previously, with individual nosebleedslasting hours requiring hospital admissions, blood transfusions and in all cases treatment discontinuation, occurred in5/14(35.7%) Rivaroxabanepisodes compared to 3/15(20%) Apixabanepisodes and published rates of ~5% for warfarin and heparin. Conclusions: Currently, conventional heparin and warfarin remain first choice anticoagulantsin HHT. If newer anticoagulants are considered,although study numbers are small, at this stage Apixaban appearsto be associated with lesser bleeding riskthan Rivaroxaban.