Objective: This study reports the use of an interactive computer program to instruct vicarious exposure and ritual prevention for obsessive-compulsive disorder (OCD). Method: Thirteen OCD volunteers and 10 non-OCD volunteers completed three 45-minute sessions at weekly intervals. Subjects with OCD completed the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), the Padua Inventory (PI) and the Beck Depression Inventory (BDI) 1 week prior to and 1 week after the three computer treatment sessions. Non-OCD subjects only completed these measures at baseline, allowing confirmation that they had no significant level of OCD symptomatology. Results: In the OCD subjects, scores fell significantly on the PI and BDI, and Y-BOCS scores fell non-significantly. Engagement in vicarious exposure with ritual prevention improved from sessions 1-3. Compared to the non-OCD participants, OCD subjects did less vicarious exposure in session 1 but not sessions 2 and 3. Performance of vicarious exposure by OCD subjects in session 1 correlated with pre-post improvement in PI and BDI scores. Conclusions: The vicarious exposure program may have a role to play as an adjunct in behaviour therapy.