Background: Obsessive-compulsive disorder (OCD) is a psychiatric disorder in which people experience repetitive, unwanted thoughts, called Obsessions and repetitive actions in which they cannot get rid of it, called Compulsions. Aim: to get the prevalence of OCD among psychology students at the university of Garmian and to compare the prevalence of OCD among grades, age groups and gender of the students. Method: a cross-sectional study design, purposive sampling method, using Yale Brown OCD Scale (YBOCS) to collect 102 samples from psychology students. Results: the severities of OCD were mostly moderate and sever. The mean OCD score was 21, with a standard deviation of 5.87, minimum 4 and maximum 33, and the range was 29. Conclusion: OCD is very common among psychology students, the moderate and severe are the most common severities. There are no significant differences between males and females, but differences in severity among studying grades. Future studies with different assessment tools and larger sample size are recommended with awareness programs about OCD.