Pterygium is a common disorder of ocular surface with unknown etiology and pathogenesis. The epidemiological studies around the world have shown that the prevalence rates range from 0.3% to 37.46%. Pterygium is related to geographic setting, sunlight and ultraviolet exposure, age, gender, economic situation, dry eye syndrome and others. The purpose of this review is to present a summary of the more recent literature about the epidemiological study, paying particular attention to prevalence and risk factors of pterygium.