A recent (and continuing) epidemic of chancroid in Houston has included morphologic variation in the disease, including so-called dwarf, classic, giant, transient, follicular, phagedenic, and pseudogranuloma inguinale types. Most cases were clearly acquired by unprotected sexual encounters with local prostitutes. The strain of Haemophilus ducreyi responsible for this outbreak was relatively easily cultured on routine media; unexpected sensitivity of this strain to vancomycin rendered the recommended "selective" growth medium much less optimal for isolation. Therapeutic success uniformly followed the use of intramuscular ceftriaxone sodium; one case responded to oral ciprofloxacin hydrochloride.