Floppy eyelid syndrome (FES) is a recently recognized entity, originally described in obese men with easily everted upper eyelids and chronic ocular irritation. Although the eyelids are primarily involved, other ocular structures such as the conjunctiva and cornea are frequently affected and cause much of the morbidity. Recent studies have found an interesting association with obstructive sleep apnea (OSA) and with chronic diseases such as hypertension and diabetes. The association of FES with OSA has both diagnostic and therapeutic implications; FES may be a presenting symptom in patients with undiagnosed OSA, and, in addition, treatment of obesity and OSA may have a favorable effect on the course of FES.