Objectives: Obsessive-compulsive disorder is one of the most common psychiatric disorders that cost a lot for the patient and the community. An important factor that is supposed to be associated with severity of OCD symptoms is emotion dysregulation. Thus, the purpose of this study was to examine different aspects of emotion dysregulation on the severity of OCD symptoms.. Methods: It was a descriptive-correlational study. 477 students of universities of Tehran were selected and completed Difficulties in Emotion Regulation Scale (DERS), Acceptance and Action Questionnaire (AAQ-II), Perseverative Thinking Questionnaire (PTQ), Obsessive-Compulsive Inventory Revised (OCI-R), Generalized Anxiety Disorder assessment (GAD-7) and negative affect subscale of (PANAS). Data was analysed by Pearson correlation, multiple hierarchical regression analysis and ANOVA. Results: The result shows that among different aspects of emotional regulation, impulse control difficulties and experiential avoidance predict the severity of OCD even after elimination of high levels of GAD and controlling of negative affect. In addition, participants with heightened GAD symptoms had significantly higher scores on Goal-directed behaviour and limited access to emotion regulation strategies than participants with heightened OCD symptoms. Conclusion: Our findings suggested that emotion dysregulation explains partial contribution of the psychopathology of OC symptoms in nonclinical people. However, in clinical condition it would be a considerable factor that mediates levels of severity, likewise other, emotion disorders. Future research will be needed to examine preventive and therapeutic role of emotion regulation in obsessive–compulsive symptom dimensions.