The last twenty years, the incidence of invasive fungal infections (IFI) has risen dramatically due to the prolongation of survival of patients with multiple risk factors for fungal infections. Amphotericin B was for more than 40 years the gold standard for almost all IFI, but toxicity and resistance, especially of new and emerging pathogens remained important issues. Fluconazole and itraconazole have also the same disadvantage of resistance. Voriconazole, a new triazole antifungal has offered an additional option, but the problem of resistant aspergillosis, and zygomycosis remains. Echinocandins (caspofungin, micafungin and anidulafungin) are active only against Candida and Aspergillus spp., but not against Fusarium, Scedosporium and Zygomycetes. Posaconazole is the most recently approved triazole with broad spectrum activity against Candida spp., Aspergillus spp., Cryptococcus neoformans, Zygomycetes, dermatiaceous, dimorphic, and other fungal pathogens. Interestingly, posaconazole is active against Candida spp., resistant to fluconazole and itraconazole, and Aspergillus fumigatus resistant to fluconazole itraconazole, amphotericin B, and voriconazole. The results from clinical trials of posaconazole as salvage treatment are encouraging. Multicenter clinical trials have also established its role in the prophylaxis of (IFI) in the severely immunocompromised patients such as those after hematopoietic stem cell transplantation (HSCT) who developed graft versus host disease (GVHD), as well as the neutropenic patients with an acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS) after myeloablative chemotherapy. Posaconazole has pharmacokinetic advantages and low side effect profile, which are very important, especially in the seriously ill population.