The authors present 10 cases of histoplasmosis, 3 due to H. capsulatum, and 7 to H. duboisii. The presenting signs were stomatological or laryngeal with H. capsulatum, and ganglionic, cutaneous, or skeletal with H. duboisii. Diagnosis was confirmed by the discovery of histoplasms in the lesions: 7 times the examination of a needle biopsy sample was positive; in 8 cases out of 10, culture on Sabouraud's medium was positive; in 3 cases out of 4 the inoculated hamster showed the presence of a histoplasmosis. Histological examination of lesions biopsies demonstrated histoplasms in the 9 cases studied. The intradermal reaction to histogical examination of lesion biopsies demonstrated histoplasms in the 9 cases studied. The intradermal reaction to histoplasmin, positive in only 1 out of 7 cases, and serological tests which showed precipitating antibodies in only 4 cases out of 10, are of very little diagnostic value. All patients were treated with amphotericin B, sometimes associated with clotrimazole (3 cases), miconazole (1 case), and rifampicin (2 cases). Two relapses occurred, one, after too soon an interruption of treatment relapsed two months later, and the other followed 18 months after a total dose of 4,200 mg of amphotericin. Surgical treatment of active subcutaneous ganglionic and bony foci may be necessary, and was employed in three cases, with a favourable result in a case of severe disseminated histoplasmosis.