How effective is psychotherapy for treating obsessive compulsive disorder (ocd)?

Studies vary in the: success rates they report. The best tx for OCD seems to be a combination of meds and behavior therapy--particularly de-sensitization or re-conditioning response therapy. Recent evidence suggests that behavior therapy alone may be just as good without meds. Here's a lay reference to start: http://en.wikipedia.org/wiki/Obsessive%E2%80%93compulsive_disorder#Behavioral_therapy

Yes certain approach: A type of therapy called exposure therapy can be very effective with OCD. In this process the therapist challenges the client to take small steps in exposing themselves to adopting their behavior and disputing their ruminating thoughts and then empowers them to see the results. Small gains in capability accumulate and the client begins to have alternative ways to dispute thinking and make choices.