Introduction: The aim of our study is to compare the attachment characteristics and the theory of mind abilities measured by the Eyes Test between social anxiety disorder (SAD) patients and healthy controls. Another aim of our study is to investigate the relationship between attachment characteristics, theory of mind abilities and disease severity in patients with SAD.Method: 47 consecutive patients with SAD and 50 healthy controls were recruited for the study. Sociodemographic data form, SCID-I Structured Clinical Interview form Patient Version, Beck Depression Inventory (BDI), Reading Mind in the Eyes Test (Eye Test), Liebowitz Social Anxiety Scale (LSAS), Experiences in Close Relationship Inventory (ECR) and State-Trait Anxiety Inventory (STAI) were administered to all participants.Results: The BDI, LSAS anxiety and avoidence, ECR and anxiety and avoidance, STAI state and trait anxiety scores of the SAD group were higher than the controls, but the Eyes Test scores were lower. It was observed that the Eyes Test score difference between the two groups survived when controlled for BDI and STAI state and trait anxiety scores. In the SAD group, both ECR anxiety and avoidance scores were associated with LSAS anxiety and avoidance scores. Eyes Test scores were associated with LSAS anxiety and avoidance scores. In regression analysis, it was observed that the Eyes Test, ECR anxiety and avoidance scores effected both the LSAS anxiety and the LSAS avoidance scores.Conclusion: In SAD patients, the theory of mind functions was impaired when compared to healthy controls, and this difference has been found to be independent of anxiety or depression levels. Attachment anxiety and avoidance dimensions have negative effects on SAD disease severity. The fact that the theory of mind ability is inversely related with SAB severity suggests that interventions to improve social cognition might have a potential to decrease the severity of disease in SAD.