Background <p>Thalassemia is a blood disorder that is transferred down through the generations. It has a negative impact on physical functioning of children and affect their social relationships and mental health. HBM has great potential in preventing thalassemia and its complication and promoting health level<b>.</b></p> Aim of the study <p>To evaluate the effect of health belief model among mothers of children with thalassemia.</p> Design <p>A Quasi-experimental research design was utilized.</p> Setting <p>The study was conducted at the outpatient haematology clinic at El-Menofia University Hospital.</p> Subjects <p>A purposive sample of 106 mothers was used. Tools: Two tools were used to conduct this study 1^st Tool: interviewing questionnaire, 2^nd Tool: Health belief model scale.</p> Results <p>53.8% of children had a family history of thalassemia, and there was improvement in total knowledge of mother’s knowledge as in preprogram was 28.4% and improved to 76.4% post program, and 72.6% in follow up. There were improvement in mother’s practices in caring of their children with thalassemia as in preprogram was 29.2% and improved to 80.2% post program, and 76.4% in follow up, and their health beliefs regarding thalassemia were improved as in preprogram was 17.0% and improved to 77.4% post program, and 73.6% in follow up.</p> Conclusion <p>There was highly statistically significant with positive correlation between total knowledge and total practice pre, post and Follow up. Also, there was highly statistically significant with positive correlation between Total knowledge and Total health beliefs pre, post and Follow up and positive correlation between Total practice and Total health beliefs pre, post and Follow up, this indicates that the mother’s knowledge, practices, and beliefs regarding thalassemia were improved by the program.</p> Recommendation <p>The study recommended that, provide support and education programs for parents to improve the care provided to children with thalassemia.</p>