Ulcerative genital disease in the United States is commonly due to herpes simplex or syphilis. Until recently, chancroid, an infection caused by the gram-negative streptobacillus Haemophilus ducreyi, was infrequently diagnosed. Continuing immigration, however, has reintroduced the disease into this country, and urban outbreaks have been associated with contact with infected prostitutes. Extensive resistance has made previous antimicrobial agents ineffective. Evaluations of multiple antibiotics and varied dosing schedules have been undertaken in an effort to circumvent this resistance. Clinicians treating patients with genital ulcerations must be aware of this disease and its geographically variable antibiotic sensitivities. Recent evidence demonstrating an association between seropositivity for the human immunodeficiency virus and ulcerative genital disease places additional importance on the timely diagnosis and appropriate treatment of chancroidal ulcers.