['Naturally occurring chancroid is usually more prevalent in men than in women.', 'To examine whether there were gender differences in susceptibility to Haemophilus ducreyi infection by analyzing the papule and pustule formation rates for men and women who were experimentally inoculated with Haemophilus ducreyi.', 'Ninety volunteers were included in the analysis. A total of 189 sites were available for estimation of the papule formation rate, and 166 sites for estimation of the pustule formation rates using logistic regression modeling.', 'Although there were no gender differences in papule formation rates, the women had significantly lower rates of pustule formation than the men after adjustment for the estimated delivered dose.'] Are men more susceptible than women to pustule formation in the experimental model of Haemophilus ducreyi infection?