Myiasis is infection with a fly larva, usually occurring in tropical and subtropical areas. A 32-years-old immunocompromised woman with fever, gastrointestinal pain, cramps, vomiting; and fatigue was referred to Ghaem Hospital in Mashhad in July 2018. Entomological characterisation of cephaloskeletons, posterior spiracles of the excreted larvae and genital dissection of male fly were diagnosed as Sarcophaga (Liopygia) argyrostoma. Accidental intestinal myiasis caused by unplanned intake of dipterous larvae by contaminated food staff or water. Patients with immune deficiency may be more at risk for the threat of maggot's infestation, so in such cases, hospital standard should be more in attention. To best of our knowledge, S. argyrostoma has not been reported before in the indexed literature from Iran.