Posaconazole is the newest triazole antifungal agent. It is structurally related to itraconazole and has activity against Candida species, Aspergillus species, Cryptococcus neoformans, the zygomycetes, and other filamentous fungi. Randomized, double-blind trials have shown posaconazole to be at least as efficacious as fluconazole for the prevention of invasive fungal infections in immunocompromised patients. It has also shown promising results in the treatment of various fungal infections refractory to other antifungal therapy. The dose of posaconazole is 200 mg orally three times daily for the prevention of invasive fungal infections and 800 mg daily in two to four divided doses for the treatment of invasive fungal infections refractory to other antifungal treatment. All posaconazole doses should be given with food or a nutritional supplement to enhance absorption. The most common adverse effects reported with posaconazole therapy were fever, diarrhea, nausea, vomiting, and headache. Instances of elevated liver enzyme levels, hyperbilirubinemia, and hepatocellular damage were also noted in clinical trials, and these laboratory values should be monitored during treatment with posaconazole.