Two patients, a 34-year old man-to-woman transsexual and a 32-year-old man, with aids presented with pulmonary symptoms, fever, serious weight loss and an oral ulcer. A third patient, a 16-year-old boy, had signs of transverse myelitis and meningitis without immunodeficiency. All were South American citizens and had disseminated histoplasmosis. After antifungal treatment they recovered, although the third patient remained a wheelchair user. If pulmonary or miliary tuberculosis is suspected in a patient originating from South America, histoplasmosis should be considered. Oral ulcers and skin lesions can be diagnostic clues. Specific stainings of direct preparations and longer-lasting cultures of various materials, especially of biopsy samples, then provide the diagnosis.