Background: Reassurance seeking is particularly prominent in obsessive-compulsive disorder (OCD) and may be important in OCD maintenance. Aims: This study used a new self-report questionnaire to measure the range of manifestations of reassurance-seeking behaviours, describing their sources from which they seek, frequency, process (how they seek), and consequences (as opposed to triggers and motivations). This study also attempts to identify the degree to which reassurance is specific to OCD as opposed to panic disorder. Method: Reassurance Seeking Questionnaire (ReSQ) was administered to 153 individuals with OCD, 50 individuals with panic disorder with/without agoraphobia, and 52 healthy controls. The reliability and validity of the measure was evaluated and found to be satisfactory. Results: Reassurance seeking was found to be more frequent in both anxiety disorders relative to healthy controls. Individuals diagnosed with OCD were found to seek reassurance more intensely and carefully, and were more likely to employ “self-reassurance” than the other two groups. Conclusions: Further investigation of reassurance will enable better understanding of its role in the maintenance of anxiety disorders in general and OCD in particular.