Infections due to the fungus Petriellidium boydii, particularly deep infections, are being reported with increased frequency. The organism generally is resistant to antifungal agents. Three patients were treated with miconazole, a new drug demonstrated to be active in vitro against the fungus. Miconazole alone was effective in treating two patients. The third patient showed an excellent therapeutic result with concomitant surgery. This experience confirms the in vitro results and suggests the utility of this drug in petriellidiosis.