The HIM (Human Papillomavirus in Men) study is a longitudinal, transnational medical study of HPV occurrence. In the HIM study’s Cuernavaca, Mexico site, an ethnographic study was conducted in which study participants and their spouses were interviewed to reveal links between medical research participation and changing Mexican gender norms. The present analysis investigates the ways that the female partners of the men who participated in the HIM study felt confianza, or trust, in their HPV-related medical experiences, including pap and HPV tests. The methodology used was analysis of a subset of qualitative data consisting of three rounds of annual interviews with 24 couples and 5 women alone. Data was coded for explicit discussions of confianza and women’s discussions of themes of trust in relationship to HPV testing and diagnosis. A literature review on the history of public health in Mexico and the cultural aspects of women’s experiences of morbidity in Mexico was undertaken to contextualize the data. Findings from this research show that all participants expressed great trust in medical testing delivered through research studies, but economic class significantly influenced women’s confianza in HPV-related healthcare in public health institutions. Women with higher education, better paying state jobs and health insurance had high levels of confianza in both public health institutes and research studies. That related to their higher levels of health education and, for many, their work in state healthcare and the educational systems, which made them more likely to trust state institutions. Women who worked low wage jobs or were homemakers were in most cases uninsured, had less sexual health knowledge, and had less confianza in public health institutes. This related to commonly discussed experiences of being unable to receive adequate healthcare services or receiving what they perceived as improper or disrespectful care from state workers. However, these women had confianza in the free testing provided by research studies because they saw studies as more respectful of patients and effective in communication, as well as a way of learning more about sexual health.