Herpes simplex virus type 2 (HSV-2) is a common infection in many countries, with prevalence in some regions, such as sub-Saharan Africa, higher than in the USA. Prevalence in adult general populations in sub-Saharan Africa ranges from 30% to 80% in women, and from 10% to 50% in men. Most data from Central and South America are from women, in whom HSV-2 prevalence ranges from about 20% to 40%. Prevalence in the general population in developing Asian countries appears to be lower (10-30%). In common with the developed world, HSV-2 seropositivity is uniformly higher in women than in men and increases with age. In general, HSV-2 seroprevalence is high in populations whose behaviour leads to a high risk of acquiring other sexually transmitted infections (STIs), such as STI clinic attendees and sex workers (SWs), with some African studies reporting greater than 80% HSV seropositivity in SWs. New infections are most common among young adults, a fact that should be considered when proposing and implementing measures to reduce HSV, and possibly HIV, transmission. Currently, comparison between studies is hampered by the lack of a validated type-specific serological assay that has a similar performance across a range of populations. HSV-2 is a major cause of genital ulcer disease (GUD) in the developing world. Genital herpes is a cause of morbidity and increases the risk of HIV acquisition, due to disruption of mucosal membranes. Where possible, the aetiology of GUD should be evaluated using polymerase chain reaction (PCR), while recognizing that co-pathogens can exist in a lesion. GUD management should incorporate HIV testing and antiherpetic treatment.