Background: Social phobia is the second most common type of anxiety disorders. It is A persistent fear of one or more social or performance situations in which the person is exposed to unfamiliar people or to possible scrutiny by others. The individual fears that he or she will act in a way (or show anxiety symptoms) that will be embarrassing and humiliating. The symptoms of social phobia including nausea, slurred speech and palpitations. It can negatively affect the activity of the person. Persons with social phobia have a negative effect on social relationships and impairments in work performance. Social phobia prevalence varies between different countries and cultures.                                                                                                       Aim:To estimate the prevalence of social phobia among medical students in Saudi Arabia.  Methods:This study was conducted by using SPIN structured questionnaire and it included 1447 of medical students from different educational years. The questionnaire involved 17 questions, the total score referred to the different severity of the disease that ranged from no disease to very severe.    Results: The female percent was 61.7% and male percent was 38.3%. Students from the 7^th medical year represented the large majority of participants 25.4%. The mean score of social phobia was 37.95 ±14.17. The prevalence of mild grade of social phobia was 29%, moderate represented 24.3%, sever grade represented 19.1% and very severe represented 19.8%, higher percent of females 20.3% suffered very sever social phobia than males (19%). There was a significant difference regarding different social phobia grades and the medical years of students (P-value=0.004).                                                                                                                    Conclusion:There was a mild prevalence of social phobia between medical students with no significant difference between males and females regarding different grades of social phobia.