BACKGROUND: In Zimbabwe, socioeconomic development has a complicated and changeable relationship with HIV infection. Longitudinal data are needed to disentangle the cyclical effects of poverty and HIV as well as to separate historical patterns from contemporary trends of infection. METHODS: We analysed a large population-based cohort in eastern Zimbabwe. The wealth index was measured at baseline on the basis of household asset ownership. The associations of the wealth index with HIV incidence and mortality, sexual risk behaviour, and sexual mixing patterns were analysed. RESULTS: The largest decreases in HIV prevalence were in the top third of the wealth index distribution (tercile) in both men at 25% and women at 21%. In men, HIV incidence was significantly lower in the top wealth index tercile (15.4 per 1000 person-years) compared with the lowest tercile (27.4 per 1000 person-years), especially among young men. Mortality rates were significantly lower in both men and women of higher wealth index. Men of higher wealth index reported more sexual partners, but were also more likely to use condoms. Better-off women reported fewer partners and were less likely to engage in transactional sex. Partnership data suggests increasing like-with-like mixing in higher wealth groups resulting in the reduced probability of serodiscordant couples. CONCLUSION: HIV incidence and mortality, and perhaps sexual risk, are lower in higher socioeconomic groups. Reduced vulnerability to infection, led by the relatively well off, is a positive trend, but in the absence of analogous developments in vulnerable groups, HIV threatens to become a disease of the poor.