Myiasis is the invasion of larvae to human or animal live tissues by flies belonging to the order Diptera and families like Calliphoridae, Sarcophagidae, Oesteridae, etc. Although rare, nosocomial myiasis must be noted carefully, especially in case of hospitalized patients. A 63-year old man admitted to an ICU ward in Mashhad is investigated and presented in this research. On the 35(th) day of hospitalization, about 100 larvae 6-7 mm in length, yellow to cream and fusiform were observed around the tracheotomy site. They were identified as second instar larvae of Lucilia genus of the family Calliphoridae based on morphological characters of the larvae. However, for exact identification of the species, the emerging adults must also be tested. According to the standard key of adult flies, they were identified as Lucilia sericata.