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Aim and Background: Some of Obsessive-Compulsive Disorder (OCD) patients believe that their unpleasant thoughts can influence the external events. The aim of this study was to investigate the correlation between the contents of thought-action fusion and obsessive-compulsive symptoms in patients with OCD. Methods and Materials: In this cross-sectional correlative study 60 OCD patients selected by available sampling method. Maudsley Obsessive-Compulsive Inventory (MOCI) and revised Thought-Action Fusion questionnaire (TAF-R) were administered. Collected data were analyzed using Pearson correlation and multiple regression analysis methods. Findings: There was positive and significant association between obsessive-compulsive symptoms and TAF-R subscales (P < 0.05). The result of stepwise regression indicate that, valence of negative events was strongest predictor of washing, likelihood of negative events was strongest predictor of checking, responsibility of positive events was strongest predictor of doubt, and likelihood-self was strongest predictor of obsessional thoughts. Conclusions: The results indicated positive and significant correlation between the TAF and OCD symptoms. Thus, it seems that occurrence of cognitive bias such as TAF increases the individual&rsquo;s vulnerability to OCD.