Low frequency (1Hz) rTMS applied bilaterally and simultaneously over SMA for 6 weeks in addition to the standard treatment regimen for OCD, will lead to significant improvement in patients' symptoms. The clinical improvement detected by YBOCS, CGI and SF-36 QOLS scores will be statistically significant in active treatment group compared to sham (placebo) treatment group.

Inclusion Criteria:

• signed patient informed consent;
• primary obsessive compulsive disorder;
• YBOCS score at least 20;
• males/females 18-65yrs;
• treated with adequate dose of SSRI at least 8 weeks at some stage of illness;
• currently using adequate, stable dose of SSRI at least 4 weeks but not responding.

Exclusion Criteria:

• schizophrenia, other psychotic disorders, bipolar I, current major depressive disorder (HDRS(17)>18, substance/alcohol dependence within last 6 months;
• severe axis II;
• suicidal score>=6 on MINI;
• metallic implant in cranium;
• severe/unstable medical conditions;
• not responding to ECT or had TMS in last 6 months;
• history epilepsy;
• neurological disorder leading to increased intracranial pressure;
• severe cardiac disorder/intracardiac lines, pacemakers;