Strongyloidiasis is a frequent misdiagnosed parasitic infection in the world that caused by Strongyloides stercoralis. In Iran, the disease is predominantly reported from warm and humid climate provinces. The patient was a 54-yr-old man, originated from Khuzestan Province with a history of pemphigus and diabetes that was treated with high-dose of corticosteroid drugs before admission in a non-private hospital in Shiraz, Iran in 2014. After different primary diagnosis and administrating of several drugs, endoscopy and histopatholgical biopsy revealed a massive S. stercoralis infection in the duodenal mucosa and gastric wall. In spite treating with anti-helminthic drugs in the last days, due to using different steroid drugs, clinical manifestations of the patient were exacerbated and he was expired on the seventeenth day due to severe dyspnea. Physicians’ awareness and using various diagnosis methods like serology, endoscopy, and biopsy should be considered in the endemic areas. In suspicious cases, anthelmintic drugs should be started before the initiation of immunosuppressive therapy.