The number of infectious disease outbreaks and the number of unique pathogens responsible have significantly increased since the 1980s. HIV-positive men who have sex with men (MSM) are a vulnerable population with regards to the introduction, spread and clinical consequences of (newly introduced) STIs. After the introduction of combination antiretroviral treatment (cART), the incidence of sexually acquired hepatitis C virus (HCV) infection and human papillomavirus (HPV)-induced anal cancers have significantly increased among HIV-positive MSM. The introduction and expansion of HCV is the result of increased sexual risk behaviour and sexually acquired mucosal trauma within large interconnected networks of HIV-positive MSM in particular. With the availability of cART, postexposure and pre-exposure prophylaxis (PEP and PrEP) and direct-acting antivirals (DAAs) for HCV, less concern for HIV and HCV might require a new approach to develop effective behavioural intervention strategies among MSM. The marked rise in HPV-induced anal cancers can be ascribed to the long-term immunologic defects in an ageing population affected by HIV. More evidence with regards to effective treatment options for anal dysplastic lesions and the usefulness of anal malignancy screening programmes is urgently needed. Most anal cancers in the future generation of HIV-positive MSM could be prevented with the inclusion of boys in addition to girls in current HPV vaccination programmes.