The echinocandins comprise a major development in systemic antifungal therapy. They rapidly and irreversibly inhibit glucan synthesis in the fungal cell wall, a distinct target from azole antifungals, flucytosine and polyenes. As such, the echinocandins appear effective against triazole and amphotericin B resistant fungi. The spectrum is still not fully understood because of problems with susceptibility testing, and because of limited studies in animal models. The primary target species for clinical studies include Candida and Aspergillus, but the class is likely to have broader use. Lack of nephrotoxicity and few drug interactions make this class attractive. The major limitations at present appear to be the lack of oral formulation and uncertainty regarding the extent of the spectrum. These drugs have the potential of being significant additions to the management of mycoses in the critically ill patient.