Objective: To identify prevalence and risks factors for

syphilis and HIV among rural female sex workers (FSWs) in Cambodia and to describe differences between rural and urban FSWs. Methods: Interviews and sera were collected from 114 FSWs and tested for HIV using the Serodia-HIV test and positives confirmed with the enzyme linked immunosorbent assay. Syphilis was tested for with the rapid plasma reagin with passive particle agglutination test for detection of anti-body of Treponema pallidum. Study data were merged with data from a study of urban FSWs from Phnom Penh that applied similar questionnaires and sampling design to compare STI prevalence and behaviours. Results: 42 % of rural FSWs were HIV positive; 22 % had past or current syphilis. In multivariate models HIV was sig-nificantly associated with age>25 (OR = 6.1 95 % CI: 1.