Without proper treatment, the mortality of pulmonary mucormycosis is nearly 100%. Although the diagnosis is often made histologically, it can be suspected when patients have a reverse halo sign on computed tomography (CT) of the chest, along with the right clinical findings. We describe the case of a woman 7 months post renal transplant who presented with fevers, malaise, and chest pain. Her chest CT revealed a round, focal area of ground-glass attenuation surrounded by a complete rim of consolidation in the left upper lobe, consistent with the reverse halo sign. Pulmonary mucormycosis was diagnosed by transbronchial lung biopsy. She was successfully treated with combined medical and surgical therapies. In the context of this case, we provide a brief review of the diagnosis of pulmonary mucormycosis, with a focus on radiographic and pathologic findings.