Dissertation (MA Education)The aim of this study was to assess effectiveness of sex education in improving students’ healthy sexual behaviours in Tanzania, based on experience from Bahi district Dodoma. The specific objectives were: to assess factors that influence effectiveness of sex education programmes in terms of students’ knowledge on healthy sexual behaviours; to evaluate relevance of the available sex education programmes in achieving students’ healthy sexual behaviours; and to examine the relationship between teachers’ knowledge and students’ healthy sexual behaviours. The study involved 462 respondents whereby 84 were teachers, 318 were students and 60 were parents. The study used cross section survey design and mixed research approaches. Data were collected through questionnaires, interviews, focus group discussion and documentary review. It was revealed that many teachers were not qualified to teach sex education. Again, majority of parents were not involving themselves in the provision of sex education. Time was not adequate as it was taught as a topic. Funds were not provided. The available SEPs were relevant but their coverage was poor. Moreover, majority (74.7%) of the respondents reported that students were not able to apply knowledge of sex education to the real life. Also, the result indicated that, there is a statistically significant correlational relationship between teachers’ knowledge on effectiveness of sex education programmes and students’ awareness of healthy sexual behaviours. Therefore, this study recommends for alternative ways to improve students’ healthy sexual behaviours through provision of effective sex education in schools. This can be done through strengthening help and support systems on sex education in schools.