The antifungal agent caspofungin is the first echinocandin that has been approved in the US and in Europe for treatment of invasive aspergillosis in adult patients who are refractory to or intolerant of conventional amphotericin B, its lipid-based formulations, and/or itraconazole. It is given as a 70 mg loading dose and a 50 mg daily maintainance dose as a one hour infusion. Due to low intestinal absorption an oral formulation has not been developed. Caspofungin is active against Candida spp. and Aspergillus spp. by inhibition the synthesis of beta-(1,3)-D-glucan, a cell wall component. The drug is inactive against Cryptococcus spp., Fusarium spp., Trichosporon spp., Rhizopus spp., and Pseudoallescheria spp. In invasive aspergillosis caspofungin resulted in higher response rates compared to a historic control under standard therapy. Efficacy data on persistently febrile neutropenic patients are pending. In several multicenter randomised double blind trials on candida infections caspofungin proved to be at least non-inferior to standard therapies. Reports of combination therapy or highly effective antifungal treatment (HEAT) in limited patient numbers are promising. New trials of combination therapy are warranted.