Several sub-Saharan African countries, including Zambia, have initiated national voluntary medical male circumcision (MC) programs to reduce HIV incidence. In-depth interviews were conducted with twenty female sex workers (FSWs) in Lusaka to examine their understanding of MC and experiences with circumcised clients. Knowledge of MC was derived primarily through informal sources, with very few FSWs reporting exposure to MC educational campaigns. MC was not widely believed to be protective against HIV, however it was viewed by some as protective against STIs. Three FSWs reported having sex with recently circumcised clients, and most reported that men often used their MC status to try to convince FSWs to forego condoms. Findings suggest that FSWs, already at high risk for HIV infection, may face additional pressure toward higher risk behavior as a result of MC. As MC services are expanded, programs should support FSWs' efforts to protect themselves by providing information about what MC can--and cannot--offer for HIV/STI infection prevention.