Invasive fungal diseases have been recognized with increasing frequency as major pathogens in patients with cancer over the past few decades, as a result of new and more aggressive anticancer treatments and supportive care, and this has been especially reported for patients suffering from hematological malignancies. In these settings, typically uncommon yeasts and filamentous fungi have recently emerged as significant human pathogens, frequently as breakthrough infections in patients receiving empirical antifungal therapy or antifungal prophylaxis and with reported high crude mortality rates. The aim of this article is to discuss certain aspects of the approach to invasive fungal diseases due to uncommon yeasts (e.g., Trichosporon spp., Blastomyces spp. and Cryptococcus spp.) in patients with hematological malignancies, focusing on epidemiology, diagnosis, treatment outcomes and the role of novel antifungal drugs (i.e., new triazoles and echinocandins).