Invasive fungal infections are a significant cause of morbidity and mortality in immunocompromised host such as prolong neutropenic patients , post transplantation patients, malignancies or advanced AIDS . The majority of these infections were caused by Aspergillus species, which the first line of treatment is antifungal agent, Voriconazole , a triazole antifungal drug which was approved by the Food and Drug Administration in May 2002 for the treatment of invasive aspergillosis and refractory infections of Scedosporium apiospermum and Fusarium spp. There are two forms of Voriconazole , oral and intravenous form. The recommendation dose is 6 mg/kg twice daily for two dosages, followed by 4 mg/kg twice daily in intravenous form or a loading dose of 400 mg twice daily for two doses is used (for individuals >40 kg), followed by 200 mg twice daily, and in individuals <40 kg the maintenance dose is 100 mg twice daily in oral form.