A regional survey has been carried out in order to establish the prevalence of hereditary haemorrhagic telangiectasia (HHT) (Rendu-Osler-Weber's disease). Forty-seven patients fulfilled the proband criteria. No patient was registered due to ocular symptoms. All of the probands were subjected to ophthalmological examination in order to estimate the distribution of ocular lesions in HHT. Conjunctival lesions were found in 20 cases, and an intraocular vascular abnormality in only one case. The possibility of intraocular lesions being a component of the clincal picture of HHT or a sporadic vascular abnormality is discussed.