Inclusion Criteria:

1. Subjects: 18 years of age or above.
2. Disease definition: Anticipated or documented prolonged neutropenic (ANC<500) at Baseline or likely to develop within 3 to 5 days and lasting for at least 7 days due to: 1) Hematopoietic stem cell transplant; 2) Intensive induction-remission chemotherapy for a new diagnosis of acute leukemia, myelodysplastic syndrome; 3) Reinduction of acute leukemia after primary relapse 4) Lymphoma requiring induction chemotherapy.
3. Subjects must be willing to give written informed consent and able to adhere to dosing and study visit schedule.
4. Female subjects of childbearing potential must have a negative serum pregnancy test (beta-human chorionic gonadotropin [hCG]) at Baseline or within 96 hours before the start of study drug.
5. Female subjects of childbearing potential must agree to use a medically accepted method of contraception prior to screening, while receiving protocol-specified medication, and for 30 days after stopping the medication. Acceptable methods of contraception include condoms with/without a spermicidal agent, diaphragm or cervical cap with spermicide, medically prescribed IUD (intrauterine device), oral/injectable hormonal contraceptive, surgical sterilization (e.g. hysterectomy/tubal ligation).

Exclusion Criteria:

1. Subjects previously treated with antifungal therapy (voriconazole, fluconazole, or itraconazole) for proven or probable IFI within 30 days of enrollment.
2. Subjects who have taken the following drugs that are known to interact with azoles and that may lead to life-threatening side effects: terfenadine, cisapride, primozide, and ebastine at entry or within 24 hours before entry, or astemizole at entry or within 7 days before entry).
3. Subjects who have taken the following drugs that are known to lower the serum concentration/efficacy of azole antifungal agents: cimetidine, rifampin, carbamezapine, phenytoin, rifabutin, barbiturates, isoniazid, and vinca alkaloids (vincristine, vinblastine) at entry or within 24 hours before entry.
4. Subjects with a history of hypersensitivity or idiosyncratic reactions to azole agents or Amphotericin B.
5. Patients who are unable to take pills.
6. Subjects with proven or probable invasive fungal infection.
7. Subjects with renal insufficiency (estimated creatine clearance less than 20mL/minute at Baseline or likely to require dialysis during the study).
8. Subjects having ECG with a prolonged QTc interval by manual reading: QTc greater than 500 msec. at Baseline.
9. Subjects with moderate or severe liver dysfunction at baseline, defined as aspartate amniotransferase (AST), alanine amniotransferase (ALT) and / or a total bilirubin level greater than 3 times the upper limit of normal (ULN).
10. Women who are breast feeding, pregnant, or intend to become pregnant during the course of the study.
11. Prior enrollment in this study.