Obsessive Compulsive Disorder (OCD) is a neuropsychiatric brain disorder disease and diagnosis, treatment process of the disease is used EEG analysis. Recent studies suggested that the OCD is caused by dysfunction in brain's frontal lobe. The GFS that was developed as a novel synchronization criteria, computes phase difference between neural oscillations in the brain. Studies were published that indicates fall of GFS values. In this study, it was investigated how OCD effect phase difference between neuronal oscillations. For this purpose, results of the GFS method was applied to 19 channels EEG, indicates OCD decrease of neural synchronization in brain's frontal lobe at Delta and Beta 3 frequency bands..