BackgroundMucormycosis is a severe and fatal fungal infection in patients with coronavirus disease 2019 caused by Mucorales. Here we present a case of a 63-year-old man with coronavirus disease 2019 infection, along with rhinosinusitis mucormycosis caused by Rhizopus delemar.Case presentationA 63-year-old Iranian man suffering from a coronavirus disease 2019 infection with symptoms of cough, shortness of breath, and generalized body pain. On the basis of the clinical manifestations, such as headache, a history of black nasal discharge, nasal hypoesthesia, facial swelling, numbness, nasal obstruction, presence of necrotic lesions on the nasal passages on physical examination, and abnormal computed tomography scans of paranasal sinuses, the patient underwent surgical debridement. Direct microscopy of specimens obtained from the paranasal sinuses, and subsequent isolation and identification, revealed a rhinosinusitis mucormycosis caused by R. delemar. Despite therapeutic measures, such as sinus debridement surgery and antifungal therapy with amphotericin B injection (50 mg/day), the patient died after 35 days of hospitalization.ConclusionIn this report, we present the first documented case of human infection with R. delemar in a patient with coronavirus disease 2019 infection, who also exhibited rhinosinusitis mucormycosis. R. delemar appears to be an emerging agent of rhinosinusitis mucormycosis in this region. Furthermore, prompt diagnosis and the exploration of alternative antifungal treatments, beyond amphotericin B, may be crucial for effectively managing patients with R. delemar infections.