Summary Thirty consecutive patients with severe scleritis or episcleritis were admitted as in-patients to the Medical Ophthalmology Unit and assessed for systemic disease. There were seventeen women and thirteen men. The mean age was 53 with a median of 57 (range 23-83). Eighteen of the patients had scleritis: eleven of these had evidence of connective tissue disease and three of them had temporal arteritis. Twelve patients had episcleritis: six of them had a collagen disease and one of them developed temporal arteritis. This high incidence of temporal arteritis in association with scleritis has not been previously reported. It is important to diagnose and treat overt temporal arteritis early with parenteral steroids so that ischaemic papillopathy can be avoided. A higher incidence of collagen diseases than previously described is reported in episcleritis. It is thought that this is secondary to selection since patients with the usual self-limiting episcleritis are not normally referred for further in-patient investigation. In no patient was more than one significant diagnosis made. There was no significant medical illness in only 11% of patients with scleritis and 33% of patients with episcleritis. The majority of the non-collagen diseases (e.g. hypertension) were not previously recognized. In none of the patients with temporal arteritis was the diagnosis made before admission. It is concluded that full examination and investigation for underlying disease is indicated in both scleritis and severe episcleritis.