The relationship between the condition of spontaneous subconjunctival haemorrhage (SCH) and hypertension was investigated. Seventy eight patients with SCH and 78 controls with unrelated ophthalmic conditions were compared. Blood pressure (BP) was significantly higher at presentation in the group with SCH at 149 (SD 27)/89 (SD 15) versus 142 (SD 25)/81 (SD 12). The proportion of hypertensives by WHO criteria (systolic blood pressure > 160 and/or diastolic blood pressure >95) was 46% on presentation compared with 23% of the control group. The morphology of the lesion did not influence the association with hypertension although there was a suggestion that the group with raised haemorrhages had a tendency to higher systolic blood pressure. It is recommended that all patients with SCH have their BP checked; this will result in the diagnosis of a significant number of new hypertensives.