Sexually transmitted infections (STIs) are notable for their fastidious requirements for transmission and growth in the laboratory and for their high physical and psychosocial morbidity. The combination of subtle or absent symptoms and stigma preventing the seeking of health care, leaves many infections undiagnosed. The development of nucleic-acid amplification tests heralded a new era in sensitive and robust diagnostic procedures for STIs. Unfortunately, many of these tests are not commercially available or are too expensive for the populations that need them most. Single-dose oral azithromycin has improved the treatment of several bacterial STIs, but quinolones are rapidly becoming ineffective for gonorrhoea. Self-treatment of genital warts with podophyllotoxin or imiquimod preparations is attractive to patients and might be cost effective for health services. The prospect of effective vaccines against genital papillomaviruses in the near future is real. Such vaccines could reduce the global incidence of some anogenital cancers. Episodic treatment of genital herpes is getting easier and cheaper, and suppressive treatment can reduce transmission to regular sexual partners. A vaccine against herpes simplex virus type 2 has shown some limited efficacy. Ultimately, better control of STIs, and reduction of their contribution to the spread of HIV, will require a broad health-sector response with adequate resourcing, and a change in social and political attitudes.