ObjectiveThe role of the male partner in reproductive health and HIV interventions is attracting greater recognition. This research examines how men respond to the challenges of HIV and Prevention of Mother to Child Transmission (PMTCT) (of HIV) with reference to their various discourses of masculinity and disease, and their responses to modernity. Methods Interviews were conducted with key informants (12) and male community members (23) in rural Tanzania. These interviews were analysed according to the principles of Grounded Theory. In addition, 445 men of reproductive age were surveyed. A further group of men (46) whose partners had participated in PMTCT were also surveyed. Bivariate analyses were performed with reference to general HIV knowledge, PMTCT knowledge and stigma. Regression analyses were performed with reference to PMTCT knowledge and stigma. Results Nearly all men expected their partner would seek their permission before participation in Voluntary Counselling and Testing (VCT) and PMTCT. Engagement with VCT and PMTCT were more congruent with modern discourses of disease, an equitable masculinity and an engagement with modernity. Media were demonstrated to be powerful mediators of these facilitating influences. Fear was identified as a powerful barrier to men’s engagement with PMTCT. With greater proximity to HIV, as marked by caring for a relative with AIDS or receiving HIV information from a health worker, men expressed more stigmatising attitudes toward HIV-infected people. PMTCT programs, by moving HIV status from an invisible to a visible status, challenged and threatened men. In addition, men whose partner had participated in PMTCT programs expressed a less equitable masculinity and were more supportive of traditional approaches. Conclusions Men’s responses to the implications of PMTCT need careful consideration in planning and strategising PMTCT programs. In this setting, fear seemingly limits engagement with practices based on modern discourses of disease and their programs of PMTCT. Understanding and engaging the support of men as partners and as community members are likely to reduce the barriers to women’s participation in PMTCT. Until these wider issues of fear and gender relations are acknowledged, addressed and engaged, the opportunity of PMTCT will be feared rather than accepted.