This study examined female sex workers’ evaluation of ethically relevant experiences of participating in an HPV4 vaccine clinical trial conducted in Lima, Peru. The Sunflower Study provided all participants with HPV testing, treatment for those testing positive, and access to the vaccine for all testing negative. Themes that emerged from content analysis of interviews with 16 former participants included the importance of respectful treatment and access to healthcare not otherwise available and concerns about privacy protections, the potential for HIV stigma, (...) and poststudy abandonment. (shrink)