Background Pterygium is an important public health problem. The prevalence rates of this disease varies widely from 1.2% to 23.4%. Aim To determine the prevalence rates and the associated risk factors of pterygium in the high-altitude area - Ta'if city, Saudi Arabia. Material and method A cross-sectional study was carried out from September 2018 till September 2019 at the ophthalmology outpatient clinics of King Abdul-Aziz Specialist Hospital, Ta'if area. Results Prevalence rate of pterygium in the high-altitude area, Ta'if city, Saudi Arabia was 2.4%. It is significantly higher in older patients belonging to the age group of more than 40 years. As for gender, it was significantly higher in male patients compared to females (2.6% vs. 1.9%). Pterygium prevalence was significantly higher among patients with outdoor occupations compared to indoor occupations (2.9% vs. 2.1%), and among patients with sunlight exposure during daily activities for more than 5 hours (2.6% vs. 2%) (p =< 0.05). Conclusion The overall incidence of pterygium in Al-Ta'if area, Saudi Arabia, was 2.4% but still lower than overall worldwide incidence (10.2%). There was an increased incidence of pterygium with age, high-altitude areas, rural areas, outdoor occupations, which is directly proportional to dose of sunlight exposure. Furthermore, smoking might be reported as a protective factor against pterygium.