Introduction: Numerous clinical studies have been performed to help realizing basic fundamentals of social anxiety disorder in past two decades. Role of recognition in forming and continuity of social anxiety disorder has been a center of attention for a long time. This study was designed to compare attention bias toward emotional faces in social anxiety disorder patients, generalized anxiety disorder patients and normal people. Method: This causal-comparative study was performed on 15 social anxiety disorder patients, 10 generalized anxiety disorder patients and two normal people selected by available sampling among patients of psychiatric centers and clinics of Shiraz in year 2009. Study units recognized positive and negative emotional faces among neutral faces by computerized task of emotional face detection in crowd. Data was analyzed using variance analysis with repeated measures by SPSS 17. Results: Social anxiety disorder patients showed more avoidance from positive emotional faces and had more attention bias to negative emotional faces in compared to normal people. There was significant difference in differentiation of emotional faces and reaction times among groups depended on number of presented faces based on face types. Conclusion: Social anxiety disorder patients interpret smiling faces as a threatening stimulant and avoid them therefore, they detect the location of negative faces more correctly than positive faces as a behavioral avoidance strategy.