Scedosporium is rare but recognized as a cause of fatal infection, especially in immunocompromised hosts. They are ubiquitously present in soil, sewage, and polluted water. Scedosporium infections have been frequently reported from Spain, likely due to climatic factors. Isolates from the United States are frequently identified from California. In reported cases, 25% was Scedosporium isolation of little clinical importance, 25% was localized in immunocompetent patients, and the remaining 50% was disseminated diseases in immunocompromised patients. Among isolated species Scedosporium prolificans is the most common, followed by S apiospermum. S apiospermum is the asexual form of Pseudallescheria boydii. After subcutaneous implantation or inhalation, this fungus is pathogenic and responsible for sinusitis, corneal infection, skin infections, arthritis, osteomyelitis, and brain abscess. It can also cause a wide range of pulmonary presentations, such as allergic bronchopulmonary disease, fungus balls, and invasive disease. Differential diagnosis with Aspergillus species is difficult on histologic examination because both fungi display thin, delicate, septate hyphae branching at acute angles. The definite diagnosis of scedosporiosis requires cultures with recognition of characteristic microscopic morphology.