Background: Obsessive- Compulsive Disorder (OCD) global prevalence is 1.8%. Untreated OCD is associated with significant educational, familial, and social dysfunctions and increased risk for other psychological and psychiatric disorders. Sadock BJ, (Sadock V.; 2016. Lack C, Storch E, Keeley M, Geffken G, Ricketts E, Murphy TK et al. 2009). For patients with obsessive compulsive disorder (OCD)., Cognitive Behavioral Therapy (CBT) has been described as the first line of treatment. To improve outcomes new targets of intervention have been suggested (Veale et al., 2015). Aim of study Examine the efficacy of Schema Therapy on obsessive symptoms among patients with obsessive-compulsive disorder. Research hypothesis: Patients with obsessive-compulsive disorder who attend Schema Therapy sessions exhibit lower level of obsessive symptoms compared to those scored before attending the schema therapy sessions. Setting: The study was conducted in the psychiatric outpatient clinics of the Main University Hospital, which is affiliated to the Faculty of Medicine, Alexandria University. The clinics provide free treatment services for patients suffering from neuro-psychiatric disorders. Sampling: The G*Power Windows. 3.1.9.7 Program was used to estimate the sample size using the following parameters: about 30 outpatients with OCD per 3 months, effect size f = 0.50, α err. prob. =0.01, Power (1-β err. prob.) = 0.99, number of groups=1 and number of measurements= 4. The program revealed a sample size of 10 patients minimum and 12 patients maximum. Results: It can be noticed that the mean score of the severity level of OCD in the study group significantly decreased from 32.38±5.84 at the first measurement before the intervention to 18.07±3.70 after implementing the schema therapy with a statistically significant difference (F=55.04, P=0.000), with effect size of 82.1%. Conclusions: The previous results reveal the efficacy of schema therapy for patients suffering from obsessive compulsive disorder. This intervention helps these patients learn new skills and use more adaptive strategies to deal with early maladaptive schemas, to gain awareness about those early maladaptive schemas and how to control emotions associated with them. Recommendations: Discharge plan for patients with obsessive compulsive disorder should include health teaching about early maladaptive schemas and how to respond to those emotion that are related to each schema as well as connect those early maladaptive schemas to associated symptoms, and consequently foster rehabilitation and adaptation to community.