The objective of this study is to evaluate the efficacy, safety and toleration of voriconazole in the treatment of systemic or invasive fungal infections due to fungal pathogens for which there is no licensed therapy or that are unresponsive or intolerant to treatment with approved systemic antifungal agents. This trial is an extension of the Phase III multicenter, open label study investigating the utilization of voriconazole for the treatment of systemic or invasive fungal infections. Enrollment is targeted for 100 patients to be recruited from multiple centers. The patient population will consist of patients with proven deeply invasive fungal infection for which there is no licensed therapy or if the patient is failing or intolerant to treatment with approved systemic antifungal agents and currently on the voriconazole (99-C-0094) protocol. Voriconazole will be administered intravenously at 3-4 mg/kg q 12 hours or orally at 200-300 mg BID. Efficacy will be evaluated by clinical, radiological and microbiological response.