Forty six patients with paramacular retinal telangiectasis were reviewed; unilateral telangiectasis was present in 26 and bilateral disease was present in 20. Patients with unilateral macular telangiectasis had the more extensive vascular involvement associated with exudation and were more likely to have peripheral telangiectasis. Bilateral macular telangiectasis was associated with pigment epithelial changes and sub-retinal scars. Visual acuity was mildly reduced in the majority of patients; severe loss of vision was most frequent in patients with bilateral macular disease. The evolution of vascular changes was very slow and only 5 patients lost vision of two lines or more during an average period of 40 months. The high incidence of peripheral changes in unilaterally involved patients implies the possibility of a primary defect of the retinal vessels in these patients. There is evidence to suggest that there may be a primary defect of the retinal pigment epithelium in some patients with bilateral involvement.