Background; Sudden infant death syndrome is the sudden unexplained death of an infant less than one year of age which remains unexplained after a thorough investigation of clinical history. The aim of this study was to evaluate the effect of educational intervention based on Health Belief Model about prevention of sudden infant death syndrome. Subjects and Method: A convenience sampling of sixty mothers and their infants participated in the study. The study was conducted at Pediatric Medical Department and Pediatric Outpatient Clinic of Tanta Main University Hospital. Three tools were used to collect data: Sociodemographic characteristics and structured interview schedule, Reported Safe Sleep Questionnaire, and Health Belief Model of mothers related to sudden infant death syndrome. The results revealed that there was a statistically significant improvement of mothers' knowledge about Sudden Infant Death Syndrome after health education. The mean scores of mothers' total health belief constructs increased after health education. The study concluded that there was a positive significant improvement in mothers' knowledge, reported sleep practices as well as health beliefs about sudden infant death syndrome after health education. Recommendations: Nurses should provide mothers with information about safe sleep recommendations to prevent sudden infant death syndrome especially young and inexperienced mothers.