In the current proposal, in a randomized clinical trial, the investigators aim to further evaluate the efficacy of rTMS in OCD in a larger sample size and for a longer period. Studies into the efficacy of rTMS in other psychiatric disorders such as depression have consistently shown that extension of the treatment to four weeks significantly increased the effect size. In the pilot study, the investigators applied rTMS for only two weeks. Although all patients consistently showed improvement in their symptoms, none of them showed complete remission of their OCD. Here, the investigators hypothesize that longer duration of rTMS treatment will have greater benefit in OCD symptom reduction.