: HIV and Herpes simplex virus type-2 (HSV2) are strongly associated, although mechanisms are not fully understood. An HIV prevention trial allowed re-examination of this association at individual and community levels.<br/> : HPTN 071 (PopART) evaluates a combination prevention intervention in 21 urban communities in Zambia and South Africa. To measure impact on HIV incidence, a cohort of ~2,000 adults (18-44y) was selected randomly from each community. Baseline data on socio-demographic characteristics, behaviour and HIV/HSV2 serology were used to examine the association between HIV and HSV2. At community-level, HIV prevalence was plotted against HSV2 prevalence.<br/> : 38,691 adults participated. HSV2 prevalence in women/men was 50%/22% (Zambia) and 60%/27% (South Africa). Estimated HSV2 incidence in those aged 18-24y was 8.06 (95%:CI:6.76-9.35) and 1.76 (95%CI:1.30-2.22) per 100/py in women and men, respectively. Six-fold higher odds of HIV were seen in HSV2-infected individuals in both sexes, after adjustment for confounders (Women:OR:6.66,95%CI: 6.07-7.31;Men:OR:6.57,95%CI:5.56-7.77). At community-level there was a strong linear relationship between HIV and HSV2 prevalence (ρ = 0.92,p&lt;0.001).<br/> : There was an exquisite association between these two infections, at individual and community levels, likely due partly to a powerful cofactor effect of HSV2 on HIV transmission. HSV2 control could contribute to HIV prevention.<br/>