Fungal infections have become increasingly more important in clinical practice due to the rising incidence of immunocompromised patients. Patients with malignancies, immunosuppression, and specific infections that alter their immunity (HIV/AIDS) have increased survival rates due to advances in the therapies of these various disorders which allow them to have a longer opportunity to contract fungal infection. Fungal pathogens have also become very important in critically ill patients treated in the intensive care unit (ICU) due to their immunosuppression and increased use of potent antibiotics. The list of medically important fungal pathogens currently includes the endemic mycosis, Aspergillus spp. and Candida spp., as the most commonly seen fungal infections in clinical practice. Other opportunistic mycoses that cause disease in critically ill patients include zygomycosis, scedosporonosis, fusariosis, and trichosporonosis. One may also see coccidioidomycosis and histoplasmosis. This group of fungal pathogens is specifically discussed because they carry a significant morbidity and mortality rate and new antifungal agents may be beneficial for their treatment.