Background: Obsessive-compulsive disorder is a mental disorder in which a person experiences unwanted thoughts, and persistence ideas that patient perceives to be inappropriate. Aim: To evaluate efficiency of nursing intervention program on psychological maladjustment, negative perfectionism, and severity of symptoms among patients with obsessive-compulsive disorder. Design: Quasi-experimental (randomized control trial) two groups were utilized. Sample: A purposive and simple random sampling technique of eighty patients with obsessive-compulsive disorder divided into forty patients in study group and forty patients in control group. Setting: The study was carried out in the Outpatients Departments, at the Psychiatric and Mental Health Hospital in Meet-khalf at Menoufia. Tool: Socio-demographic data, Brief Psychological Adjustment-6, Positive and Negative Perfectionism Scale, and Obsessive-Compulsive Inventory. Results: The study findings revealed that there were highly significant differences regarding obsessive-compulsive disorder symptoms in the study group between pre and post-program (p≤0.000) and pre-program and follow-up (p≤0.002). It revealed that there were significant relations between psychological adjustments, positive, negative perfectionism, and Obsessive-compulsive  disorder's symptoms through program phases in the study group (p≤0.000). There were no significant differences between the studied variables and control group through program phases. Conclusion: Patients with obsessive-compulsive disorder who participated to the nursing intervention program "study group" improved their symptoms, psychological adjustment, positive perfectionism, and reduced levels of negative perfectionism than those who are in the control group. Recommendations: Psychiatric nursing teams should implement the nursing intervention program for people with obsessive-compulsive disorder in order to improve their symptoms, psychological adjustment, positive perfectionism, and reduce negative perfectionism.