Purpose: To evaluate the prevalence of pterygia and its associated factors in an adult Chinese population of Greater Beijing. Methods: The Beijing Eye Study, a population-based prevalence study.. included 4439 (83.4%) of 5324 subjects living in a rural area or urban region of Greater Beijing, 40+ years of age, invited to participate. The participants underwent a standardized examination protocol including corneal photography. Results: A pterygium was detected in 169 (1.9%) eyes of 128 (2.9%) subjects. The prevalence of a pterygium was significantly associated with rural versus urban region (P < 0.001), age (P > 0.001), and male sex (P 0.04). It was not associated with level of education (P = 0.25) or refractive error (P = 0.20). Conclusions: The prevalence of pterygium in Greater Beijing is similar to 3% among Chinese >= 40 years of age. Independent associations with living in a rural versus urban region, increasing age, and male sex suggested a correlation with outdoor work.