Graves' orbitopathy (GO) is an autoimmune disorder and the main extrathyroidal expression of Graves' disease. There is a spectrum of ocular involvement in Graves' disease, from complete absence of symptoms and signs to sight-threatening conditions. The prevalence of GO varies in different published series of Graves' patients, due to confounding factors (new diagnosis vs long-lasting disease, way of defining and assessing ocular involvement, treatment of hyperthyroidism with potentially GO-modifying treatments, such as radioiodine). Recent studies, however, suggest that most Graves' patients have mild or no GO at presentation, while moderate-to-severe GO is rare, and sight-threatening GO (mostly due to dysthyroid optic neuropathy) is exceptional in non-tertiary referral centers. The natural course of GO is incompletely defined, particularly in patients with moderate- to-severe GO, because these patients require prompt and disease-modifying therapies for orbital disease. In patients with mild GO at presentation, progression to severe forms is rare, while partial or complete remission is frequent. Progression of pre-existing GO or de novo occurrence of GO is more likely in smokers. There seems to be a trend towards a decline in progression of GO, possibly due to a better control of risk factors (cigarette smoking, thyroid dysfunction, etc.) and a closer interaction between endocrinologists and ophthalmologists allowing an improved integrated management of thyroid and orbital disease.