© 2021Background and objectives: The study examines the nature of OCD-related unwanted mental intrusions (UMIs) by comparing OCD, anxiety disorders (AD), and healthy control (HC) groups. Methods: The patients with OCD (n = 50), AD (n = 59), and HC (n = 50) completed a semi-structured interview assessing UMIs, and a set of questionnaires. Results: Our results provided evidence for the cognitive content specificity of OCD-related unwanted mental intrusions (UMIs) and appraisals. Two patient groups and non-clinical participants reported at least one OCD-related UMI and the groups did not differ from each other in terms of the forms and triggers of UMIs. However, the intrusions were more distressing and persistent in the OCD patients. The patients with OCD placed higher importance on getting UMIs out of their minds and reported higher difficulty in controlling them compared to the other two control groups. Furthermore, control appraisals showed higher relevance to the distressing features of the intrusions. Conclusions: The results underlined the specificity of obsessive cognitive content and the importance of thought control-related appraisal in defining the distressful features of the mental intrusions seen in OCD. The results were discussed in light of the cognitive specificity model.