BACKGROUND Lid imbrication syndrome is an abnormality of lid apposition in which the upper lid overlies the lower lid. Patients often complain of irritation, tearing, and foreign body sensation. The condition may be difficult to diagnose. METHODS Twenty-one patients with suspected lid imbrication syndrome were compared with 21 age-matched controls. All patients were given 0.5% topical rose bengal. RESULTS The diagnosis of lid imbrication syndrome was confirmed by the presence of rose bengal staining of the tarsal conjunctiva of the upper lid margin. The amount of rose bengal staining correlated with the severity of lid imbrication. Eighteen of 21 patients had received a diagnosis previously of dry eye syndrome. Four patients had persistent epithelial defects. CONCLUSIONS Rose bengal staining of the superior lid margin tarsal conjunctiva offers an extremely reliable aid for diagnosing lid imbrication syndrome. The condition commonly presents as a dry eye or persistent epithelial defect. Treatment ranges from viscous tear substitutes to horizontal lid shortening of the upper lid.