Voriconazole is a new drug developed to treat fungal infections. As of March 1999, the drug had been studied in more than 1,900 healthy volunteers or patients with fungal infections. This study will test extended use of voriconazole in patients with serious fungal infections for which there are no approved therapies, and in patients who did not improve with or could not tolerate standard therapy. It will evaluate the drug's safety, effectiveness, and toleration in these patients.