A 75-year-old man was admitted to the intensive care unit for an acute abdominal pain associated with massive hematochezia. He had a history of type II diabetes mellitus, hypertension, hypercholesterolemia, weaned smoking, unstable angina with triple coronary artery bypass grafting, macular retinal degeneration, and benign prostatic hypertrophy. He underwent endarterectomy for left carotid stenosis. General examination reported a blood pressure of 60/40 mmHg, a heart rate of 180 bpm, a respiratory rate of 34/min, an oxygen saturation of 89% and a temperature of 38.3 C. Physical examination had reported abdominal tenderness. He was immediately treated in the intensive care unit as an acute peritonitis. The patient was intubated and received fluid resuscitation, vasopressor drugs (norepinephrine), empiric antibiotic therapy (piperacillin/tazobactam) and high dose of proton pump inhibitor. Abdominal and pelvic computed tomography (CT scan) with intravenous contrast showed a perforation of the anterior wall of the rectum (Figure 1). The patient underwent immediate laparotomy that failed to find the perforation. Temporary colostomy was performed. He had a hemoglobin level of 9.3 g/dL after transfusion of 5 units of packed red blood cells. There was a hyperleukocytosis of 14,760 elements/mm3 and a C-reactive protein of 101 mg/L. QuantiFERON-tuberculosis assay and human immunodeficiency virus (HIV) serology were negative. Several upper GI endoscopies showed multiple ulcerated lesions along the greater gastric tuberosity, on the anterior wall, 3 to 4 cm in diameter, surrounded by a budding edematous mucosa, and fragile on contact (Figure 2). Lower GI endoscopy showed a productive fistulous orifice with a whitish filamentous discharge at the anterior aspect of the rectum (Figure 3). Histopathological examination of gastric biopsy showed acute and subacute inflammatory remodeling mixed with filamentous elements suggestive of mucormycosis (Figure 4). Rectal biopsy histology was fibro-edematous remodeling, lymphoid nodular cluster, and non-specific subacute inflammation with negative Periodic Acid-Schiff (PAS). Fungal culture of secretions from the rectal fistula orifice identified the strain Rhizopus sp. Antifungal susceptibility testing reported sensitivity to liposomal amphotericin B. Chest CT scan during the hospitalization revealed bilateral pleural effusion and atelectasis. Lung scintigraphy showed recent segmental pulmonary embolisms of the right upper lobe. The diagnosis of GI mucormycosis-induced multiple gastric ulcers, rectal perforation and pulmonary embolism was retained. The patient was treated with liposomal Amphotericin B 5mg/kg/day intravenously for 6 weeks and anticoagulation with low-molecular-weight heparin and insulin therapy. Upper gastrointestinal endoscopy after 4 weeks showed healing of the gastric ulcers (Figure 5). After 6 weeks, the outcome was favorable without recurrence or other complications.