Forty seven individuals (from 16 kindreds) without prior evidence of retinal haemangiomas underwent full ophthalmological assessment as part of a comprehensive screening programme for Von Hippel-Lindau disease. Ten were known to be affected on the basis of non-ocular involvement and 37 were at 50% risk of having the abnormal gene. Seventeen angiomas were detected in 14 individuals (six affected patients and eight at risk relatives). Regular detailed ophthalmological assessment is important for all patients with von Hippel-Lindau disease and for relatives at risk of inheriting the abnormal gene.