Abstract Study question What are the attitudes/experiences of Japanese health and physical education teachers (HPETs) and Yogo teachers (YTs) in upper secondary schools (USSs) toward fertility education? Summary answer Twenty-three fertility facts were considered; teachers’ perceptions of the need to teach USS students were thoroughly high, while teaching experiences were comparatively low. What is known already In Japan, in the 2018 commentary on the national curriculum standards for health and physical education, teaching content on fertility was included for the first time. There are very few studies of schoolteachers who teach fertility, both nationally and internationally. In Japan, only one study has examined the fertility knowledge of teachers, and their knowledge was found insufficient. No studies have identified the experiences and awareness of HPETs and YTs* toward fertility education in the context of the revision of the curriculum guidelines. *YTs are specially licensed teachers in Japan to facilitate children’s development through health education in schools. Study design, size, duration This study was designed as a cross-sectional questionnaire survey. The target groups were HPETs and YTs working in all 68 public USSs in Kumamoto, Japan. Questionnaires were mailed to the public USSs in January 2020, and targeted persons were asked to post completed questionnaire in three weeks; 145 HPETs (response rate; 53.3%) and 46 YTs (52.3%) participated in this survey. The study protocol was approved by the Ethics Committee (approval number: 28-10). Participants/materials, setting, methods We selected 23 fertility facts. Teachers were asked what USS students should know by graduation, whether the teachers have teaching experience, and how much they understood these fertility facts. Simple aggregation was carried out. To assess the differences between HPETs and YTs, a chi-square analysis and a Mann–Whitney U test were conducted. The significance level was set at 5%. Main results and the role of chance In our study, 122 of HPETs (84.1%) were men and all the YT were women. Fertility facts that over 70% of teachers believe USS students should know by graduation concerned “STIs”, “smoking”, “aging” and “girls’ thinness or obesity” as risk factors of infertility, as well as “most fertile period within menstrual cycle”, “irregular menstruation”, “excessive exercise for girls”, “reasons for infertility” and other facts. On “irregular menstruation”, “girls’ thinness or obesity” and “PCOS and endometriosis” YTs showed greater motivation than HPETs (p<.05).For more than half of the fertility facts, significant differences were identified. HPETs were more experienced at teaching about “women’s aging” and “men’s aging” as infertility risk factors, “reasons for infertility”, “frequency of sperm production”, “risks of advanced pregnancy”, “relationship between advanced pregnancy and perinatal mortality” and other facts than YTs (p<.01). Meanwhile, YTs were more experienced to teach as to the effects of “irregular menstruation” and “PCOS and endometriosis” on fertility than HPETs (p<.01). Fertility facts that few teachers have taught, despite many teachers believe their students should know by graduation, were “frequency of infertile couple”, “the incidence of child’s disease by male aging” and “PCOS and endometriosis” and other facts. Limitations, reasons for caution The limitations of this study are that participants were all working at public USSs in only one prefecture in Japan, and the return rate was just over 50%. Therefore, caution should be taken when generalising the results to the general population of Japanese HPETs and YTs. Wider implications of the findings It was suggested that for HPETs and YTs to be able to conduct fertility education, seminars and teaching materials such as guidebooks and online video materials must enable them to understand fertility facts based on scientific evidence and have an ability to teach them appropriately. Trial registration number none