The activity of fluconazole and amphotericin B against three isolates of Cryptococcus neoformans was evaluated, with fluconazole and amphotericin B MICs of 2.0-4.0 mg/L and 1.0 mg/L respectively, using time-kill curve methods. Fluconazole was fungistatic against all isolates tested (<99.9% decrease in cfu from initial inoculum). The fungistatic activity of fluconazole was not enhanced by increasing the concentration of antifungal in solution. In contrast, amphotericin B was markedly fungicidal (> or = 99.9% decrease in cfu from initial inoculum). Both the rate and the extent of amphotericin B activity were enhanced when drug concentration was increased.