Sporotrichosis most commonly presents as a localized, lymphocutaneous infection that follows trauma, such as an injury from a rose thorn. In patients infected with HIV, it may be widespread and disseminated. We describe a patient with AIDS who developed disseminated sporotrichosis, a rare opportunistic fungal infection that may affect these patients. The condition remained undiagnosed because of failure to recognize characteristic histopathologic findings and failure of clinicians to interface closely with the microbiology laboratory. The condition was difficult to treat, requiring systemic administration of amphotericin. While localized sporotrichosis is an innocuous disorder that responds well to therapy, in immunocompromised hosts, it is potentially life-threatening and may require prolonged therapy with potentially toxic medications such as amphotericin B. It is important that clinicians be aware of the presentation of this unusual opportunistic infection and that they maintain close communication with pathology and clinical microbiology laboratories to ensure that proper stains and cultures are performed to avoid potential misdiagnosis. (J Am Acad Dermatol 1999;40:350-5.)