Background: Multiple sclerosis (MS) is a common neurological disease that can have devastating effects on patients' physical and mental well-being. Complying with therapy regimen is a beneficial step in improving a person's behavior while on modified life style, take medication, or follow a diet. The aim of the study: Evaluate the effect of health promotion program on therapeutic regimen compliance for patients with multiple Sclerosis. Design: A pre/posttest quasi experimental design was carried out. Setting: This study was conducted in neurology out patients' clinic at zagazig university hospital. Sample: A purposive sample of 60 adult patients with multiple sclerosis. Tools: Four tools used in the study: patient assessment questionnaire, self-care Practice checklist, compliance assessment scale, and factors affecting patients' compliance based on health belief model (HBM). Results: The study found that the age's mean and standard deviation among the studied patient was 42.03±11.23. Approximately 73.3% of them were female. About 85%, and 88.3% respectively of studied patients had satisfactory level of knowledge regarding MS, and their lifestyle habit post program. While 91.7% of them had adequate level of practice, and patients' compliance improved to 78.3% post program. Furthermore a positive correlation with a statistically significant between the overall knowledge score, total practice score, total lifestyle habits, and total health beliefs. Conclusion: It can be concluded that health promotion program for adult patients with multiple sclerosis improved patients' knowledge, which can reflect an improvement in their self-care practice and therapeutic regimen compliance, in addition to raising all constructs of the Health Belief Model. Recommendations: Incorporate the health belief model into the design of health focused interventions by enabling participants to take an active role in self-care practice.