This study investigated the implementation of sex education in both schools and families by surveying 102 primary school teachers and 105 parents of primary students in Quang Binh province, Vietnam. The findings revealed that most teachers possess a relatively good understanding of the general concept and importance of sex education and express a positive attitude toward teaching it. However, a notable proportion of teachers still confuse key concepts and lack comprehensive knowledge of the subject. Although sex education has been integrated into various subjects and extracurricular activities, teachers face significant challenges, such as students’ passivity and discomfort, insufficient pedagogical skills, limited training opportunities, and a lack of coordination between management and implementation units. On the parents’ side, while most demonstrate a basic awareness of sex education, many remain hesitant to discuss gender-related issues with their children due to limited knowledge, inappropriate methods, and time constraints. Nevertheless, the majority of parents support the integration of sex education into the primary school curriculum. These findings provide practical insights for developing targeted strategies and training programs to enhance the effectiveness of sex education implementation among teachers and parents.