Chronic blepharitis is one of the most common diseases of the eyelids, but surprisingly, it is not often recognized. Frequently, a skin disease such as seborrheic dermatitis, atopic dermatitis, or acne rosacea is the underlying cause of chronic blepharitis. Bacterial pathological lipase, cholesterylesterase production, and bacterial lipopolysaccharides are pathogenetically relevant. Only rarely do genuine bacterial infections play a role. Collarettes occur at the base of the eye lashes, and the Meibomian glands show either abundant fluid secretion or inspissated secretion with obstruction of the orifices. Chronic blepharitis can include sequelae including dry eye and corneal and lid contour changes. The basic treatment comprises attendance of the underlying dermatological disease and lid hygiene. In addition, preservative-free tear film substitutes, antibiotics, immunomodulatory agents, or even surgical intervention may become necessary.