Forty-three individuals with obsessive-compulsive disorder (OCD), 17 with generalized anxiety disorder (GAD) and 50 non-clinical controls (SC), completed the Italian versions of the Obsessive Beliefs Questionnaire (OBQ) and the Interpretations of Intrusions Inventory (III), along with measures of obsessive-compulsive (OC) symptoms, depression, anxiety and worry. OBQ and III showed an excellent reliability and temporal stability. The six OBQ subscales were reasonably distinct from each other, whereas the three subscales of the III were highly interrelated. The OBQ, and in less measure the III, discriminated between OCD, GAD, and normal controls. In the OCD cohort, the two instruments correlated moderately with a measure of obsessive-compulsive symptoms but also with a measure of worry. However, a linear regression analysis evidenced a specific relationship between the OBQ and obsessive-compulsive symptoms over and above worry. Overall, at least three cognitive domains (intolerance of uncertainty, excessive concern about the importance of controlling one's thoughts and perfectionism) seemed specific to OCD, whereas overimportance of thoughts and inflated responsibility barely discriminate clinically anxious individuals from non-clinical ones. It is concluded that OBQ and III are useful measures in Italian individuals and that more research is warranted to possibly refine these two instruments.