Invasive fungal infections are highly aggressive and occur almost exclusively in severely immunocompromised patients, such as solid organ and hematopoietic stem cell transplant recipients, patients with profound and prolonged neutropenia, patients with diabetes mellitus (particularly with ketoacidosis), and those with other conditions. The most common invasive fungal infection in these patients is invasive aspergillosis. However, use of antifungal prophylaxis, among other considerations, leads to a relative increase in non-Aspergillus invasive fungal infections, such as mucormycosis. Mucormycosis may present in a manner that clinically and radiographically resembles invasive aspergillosis, but distinguishing these 2 infections is important because the common treatment for invasive aspergillosis—voriconazole—is not active against mucormycosis. Although the diagnosis of mucormycosis often requires microbiological identification of the organism, several computed tomographic features, including the reverse halo sign, multiple (>10) nodules, micronodules, and pleural effusion, may favor the diagnosis of mucormycosis over invasive aspergillosis. Such a distinction may prove very useful when a confirmatory tissue diagnosis is not possible. The mainstay of treatment for mucormycosis includes reversal of identifiable risk factors, surgical debridement of necrotic tissue, and appropriate antifungal therapy. In selected patients, iron chelation therapy may be of benefit.