Objectives To describe regional variation in human immunodefffeciency virus (HIV) prevalence trends in the period 1994–2002 and to assess the effects on prevalence trends of residence, educational level and age, and potential interaction between these variables.

Methods The data were from the national HIV sentinel surveillance system comprising information collected using interviews and unlinked anonymous testing of blood among pregnant women attending antenatal clinics in 22 sites in 1994, 1998 and 2002.

Results There was a decline in HIV prevalence in the age group 15–24 years in the period 1994–2002 both in rural (by 11%) and urban (by 26%) areas. The decline was strongest among highly educated women. However, this overall decline masked striking differences at community (site) levels with clearly declining epidemics in many sites contrasted by increasing epidemics in some and stability in others. Urban/rural residence, age, educational attainment, marital status and parity were factors closely associated with HIV infection. Having born many children was associated with lower risk of being infected by HIV, even in the age group 15–24.

Conclusions The HIV prevalence decline in young women is likely to reflect a drop in incidence during the period. However, there were sharp geographical contrasts in trends. Such local contrasts probably indicate differences in effectiveness of preventive interventions. Understanding factors and mechanisms explaining the differences will be of critical importance to better guide preventive interventions.