Mucormycosis is an invasive fungal infection associated with high lethality, predominantly affecting immunocompromised patients, such as those undergoing solid organ transplantation. The gastrointestinal form of the disease is rare, often asymptomatic until advanced stages, and is usually diagnosed only by post-mortem methods. We report the case of a 46-year-old man, kidney transplant recipient for 19 years due to nephritis of undetermined etiology, on tacrolimus, mycophenolate and prednisone, with a recent history of neurotoxoplasmosis and cytomegalovirus infection. He was admitted in May 2024 with fever, chills and lower limb weakness. Initial tests showed leukopenia with neutropenia, and treatment for febrile neutropenia was started. He evolved with progressive clinical worsening, developing hypotension, hypoxemia and diffuse pulmonary infiltrates. Blood cultures revealed multidrug-resistant Pseudomonas aeruginosa. He progressed to death due to refractory septic shock. Autopsy revealed extensive areas of necrosis involving the esophagus, stomach and intestinal loops. Histopathological examination of the gastrointestinal tract showed broad, non-septate hyphae branching at right angles, compatible with fungi of the order Mucorales. We discuss the rarity of the gastrointestinal form of mucormycosis, especially in renal transplant patients, and the diagnostic difficulty due to nonspecific clinical manifestations. The case illustrates the importance of clinical suspicion in severely immunosuppressed patients with unexplained deterioration, reinforcing the role of autopsy as a crucial diagnostic tool in elucidating atypical fatal infectious conditions.