An increasing body of information permits certain conclusions to be drawn about the nature and magnitude of the interactions between HPV and HIV infections and their influence on the genesis of intraepithelial neoplasia and, to a lesser extent, cancer. Importantly, findings tend to be consistent across a number of independent studies. While HPV infection probably does not significantly alter the course of HIV infection, HIV-induced immunosuppression does increase the severity and duration of anogenital warts, increase their infectiousness and reduce treatment efficacy. However, in developed countries the countervailing effects of enhanced HPV infectiousness and declining rates of unsafe sexual behaviour have resulted in stable or declining incidence rates of anogenital warts. Advanced immunosuppression due to HIV infections results in highly significant increases in rates of HPV-associated CIN and AIN. In developed countries, population-based secular trend analyses point to increasing incidence rates of anal cancer in single men in areas of high HIV prevalence, but not yet of cervical cancer in women.