Several empirical studies suggest that exposure in vivo and response prevention have a differential treatment effect on the complaints presented by patients with Obsessive-Compulsive Disorder (OCD). In the present study it was hypothesized that exposure in vivo would result in a greater decrease of obsessional fear, whereas response prevention would result in a greater decrease of rituals. Forty patients, diagnosed with OCD, participated in the study. Half of the patients received exposure in vivo alone, followed by response prevention alone, and half received response prevention alone, followed by exposure in vivo alone. No differential treatment effects between exposure in vivo alone and response prevention alone could be found, although ritualistic behaviour was less strongly affected by exposure in vivo following response prevention.