OBJECTIVES: To examine the effect of neighbourhood socioeconomic factors on human immunodeficiency virus (HIV) prevalence in young women (aged 15-24 years) in Zambia. METHODS: Re-analysis of a cross-sectional, population-based sero-survey of nearly 2000 adults conducted in 1997/1998 in Ndola, Zambia. Neighbourhood-level socioeconomic status (SES) was defined using the availability of running water and electricity in addition to educational, employment and occupational characteristics of adults older than 24 years. Neighbourhood-level and individual-level risk factors were analysed with a multivariate multilevel logistic regression model using a hierarchical conceptual framework. RESULTS: Young women living in neighbourhoods of lower or middle SES had higher HIV prevalences than those from higher SES neighbourhoods [lower SES: adjusted odds ratio (OR) 2.4, 95% confidence interval (CI) 1.3-4.5, middle SES: adjusted OR 2.4, 95% CI 1.3-4.7]. Young women living near a market were at increased risk of HIV infection (OR 2.9, 95% CI 1.4-5.9), while proximity to a health centre seemed protective (OR 0.4, 95% CI 0.2-1.0). When controlling for neighbourhood factors, better education was a risk factor for HIV infection (OR 1.5, 95% CI 1.0-2.1), although it was not significant in individual-level analysis. CONCLUSIONS: Community-level factors are as important as individual-level factors in determining HIV infection in young women. Confining analyses to individual-level factors ignores the underlying causes and the modifying effect of context on individual behaviour and may even lead to different conclusions concerning the role of individual-level factors.