This paper presents a preliminary mathematical model of transmission of the HIV virus from a sexually active prostitute to her clients, and the transmission from those clients to their sexual partners. The final link in the chain is transmission from pregnant mothers to their fetuses. The goal of the study is to determine the effect that a single‐infected, very sexually active prostitute can have on a population of other uninfected adults. Assuming values for the probability of transmission at each sexual encounter and a model for client repeaters, we show that in five years, a single prostitute could be expected to infect about 20 men and about 0.8 unborn children.