Previous work1-3 has indicated that the drug amphotericin B (an antifungal antibiotic isolated from an unidentified species of Streptomyces) has antifungal activity against Histoplasma capsulatum. This has been shown both in vitro and in experimental infection. Our own previous results as well as the results of other groups have indicated that in spite of the relative insolubility of the drug definite activity against experimental histoplasmosis has been demonstrated.1-3 The hamster has been the experimental animal of choice in histoplasmosis in our experience, and for this reason it has been used in the present work to further evaluate the effect of amphotericin B in experimental disease. Previously the combination of amphotericin B with sulfadiazine had given better results than amphotericin alone. The sulfadiazine alone had little effect in our hands.1,2 The relatively insoluble nature of the drug, amphotericin B, was the most serious drawback to its use in