In the USA, an estimated one-in-two adolescent African American women have a sexually transmissible infection (STI). In addition, African American women have the second highest rates of HIV infection of any race/ethnic and gender group, and 13–29-year-old women have the highest proportion of new HIV infections compared with all other age groups. These findings represent a ‘syndemic’ for young African American women, where the STI and HIV epidemics are ‘interacting synergistically to contribute to excess burden of disease’. For young African American women, the disproportionately high STI prevalence along with behavioural, biological and social circumstances signals the potential for the HIV epidemic to become more entrenched by creating an effective and efficient pathway for sexual transmission of HIV. First, due to higher STI prevalence rates within African American sexual networks, young African American women are at increased risk for STIs and HIV. Second, the presence of certain STIs can increase the likelihood of HIV transmission by twoto fivefold. Third, adolescent women often have older male sexual partners, which can set up a link from a higher HIV prevalence network of older men to a relatively low prevalence network of adolescent women. Fourth, the increased biological efficiency of HIV transmission from male to female in heterosexual intercourse and the increased physiological susceptibility to HIV infection of young women because their cervical cells are more easily traumatised compared with older women further intensify these high-to-low-prevalence transmission dynamics. When these factors are embedded in a larger context of high HIV prevalence, a move from a concentrated to a generalised HIV epidemic becomes possible. As seen in Washington D.C., high rates of incident HIV cases among women coincided with heterosexual sex as the primary transmission mode. We need to heed the early warning signs of this ‘canary in the coal mine’. The STI rates among young African American women represent a window into where the HIV epidemic may be moving. We have an opportunity to intervene early in the epidemic trajectory; however, it is important that we develop, implement, and fund new and existing prevention for young African American women and their sexual partners that is proactive, integrated and comprehensive. Many have called for ‘combination HIV/AIDS prevention’ that integrates biomedical, behavioural and structural elements of prevention. Combination prevention should also include prevention efforts at each stage in the risk behaviour trajectory: pre-risk, initiation of risk and on-going high risk. Current HIV prevention efforts overwhelmingly target the high-risk phase with people who are already HIV-positive or, if uninfected, already engaged in high-risk behaviours. To complement these efforts, we should include prevention that targets the pre-risk phase – before risk behaviours begin, rather than waiting until risk behaviours become entrenched and difficult to change. What might a comprehensive approach to sexual health look like for young African American women? First, young women are primarily infected with HIV through heterosexual contact. We must work at both sides of the transmission equation and include men in prevention efforts, for their own prevention and as partners in reducing young women’s risk. We need to better tailor prevention and clinical services to the needs of young men, particularly young African American men, in order to draw in this often hard-to-reach population. In addition, we need to address the sometimes power-based heterosexual relationships that can put both young women and men at risk. We need to improve efforts to unite young African American men and women as partners in each other’s sexual health, while also continuing to learn from and empower women who are not able to successfully engage their male partners, particularly those with older partners. Second, with a pre-risk approach, we have the potential to raise an HIV-free generation – to stop the evolution of new cohorts at risk for and infected with HIV. We can help youth develop skills they need to avoid sexual risk over the course of their lives. Parents, guardians and families are key partners in this endeavour. They are in a unique position to provide children with early, continuous sexual health guidance throughout their sexual development, and parenting programs can support these efforts. At this formative life stage, we can work with community leaders, parents, and teachers to promote attitudes about gender, race and sexuality that support positive, healthy sexuality. For instance, we can help support models of dating relationships that are based on mutual respect and responsibility rather than CSIRO PUBLISHING Editorial