A case of Strongyloides stercoralis infection wss experienced in a 73-year old Korean female patient, was hospitalized with relapse of cholecystitis. The patient developed cough and dyspnea 17 days after the admission. On the 27th hospitalized day, diarrhoea, nausea, vomiting and abdominal pain started. A number of parasitic larvae were incubated at 25 degrees C for 2 days. Typical fork tailed filariform larvae of S. stercoralis (Bavay, 1876) Stiles and Hassall, 1902, were identified after cultivation. There was no improvement of diarrhoea after the medication with mebendazole. After the administration of thiabendazole, however, diarrhoea was stopped. On the 6th day of medication, S. stercoralis larvae were no more detected, and thereafter no larva was observed by repeated stool examinations upto 2 months after chemotherapy. The patient had the history of administration of steroid for articular rheumatism. Therefore this case seems to be a hyperinfection of S. stercoralis due to an autoinfection and to be the first report on the hyperinfected strongyloidiasis in Korea. Related literature was briefly reviewed.