Invasive fungal infections (IFI) are a major cause of morbidity and mortality in immunocompromised patients. Candida and Aspergillus are the most common fungi that lead to IFI. While invasive Candida infections are most commonly seen in patients in intensive care units (ICUs) and very low birth weight infants, aspergillosis is most frequent in immunocompromised patients, especially in patients with hematological malignancies and in those undergoing hematopoietic stem cell transplantation (HSCT). Empirical treatment should be considered in all high-risk patients with hematological malignancies suspected of having IFIs.