This study aims to evaluate the therapeutic effect of low frequency rTMS over the right DLPFC, versus right OFC versus Sham group of obsessive-compulsive disorder (OCD) patients. Sixty patients will be recruited from the out-patient psychiatric clinic of a university hospital, and randomized into three equal groups. The 1st group will receive 10 sessions of low frequency rTMS targeting right DLPFC by means of a butterfly coil, 120% RMT, 1 Hz, 3 trains, each of 500 pulses with a 40 seconds inter-train interval allowing the coil to cool. The 2nd group will receive 10 sessions of low-frequency rTMS over the right orbitofrontal cortex (OFC), the international 10-20 EEG system will be used to position the coil over the right OFC, at the right frontopolar 2 (Fp2) electrode site, using the following parameters: 120% motor threshold, 1 Hz, 3 trains, each of 500 pulses with a 40 seconds inter-train interval allowing the coil to cool. The 3rd group will receive sham stimulations with the same pulse delivery as the other groups but with the coil placed perpendicular to the scalp.