A new murine model of acute paracoccidioidomycosis, whose features include pulmonary infection with dissemination, was used to study the efficacy of currently available drugs and new agents which might be useful clinically. Two oral imidazole drugs, ketoconazole (KTZ) and Bay l 9139 (l9); two oral triazoles, Bay n 7133 (n7) and ICI 153,066 (ICI); and two polyenes, amphotericin B (AMB) and N-D-ornithyl-amphotericin B methyl ester, were studied. KTZ was superior to n7 and l9, particularly after a less lethal challenge. The polyenes could diminish dissemination, but had only modest effects on the pulmonary infection; AMB appeared slightly more effective. ICI was the most effective drug studied, approximately 5-10 times more potent than KTZ on a milligram/kg body weight basis; it had marked effects on both pulmonary and disseminated disease. These initial applications of the model to therapeutic evaluation suggest sufficient flexibility and utility, with information obtainable after relatively short experiments.