Human strongyloidiasis is a parasitic infection induced by the nematode Strongyloides stercoralis which can cause gastrointestinal disturbances. It is believed to be a zoonosis with a potential for cross infection between humans and dogs. The aim of this work was to study this cross infection. Epidemiological surveys of human intestinal parasites were carried out using direct smears and cultures in the Amami Islands during the summer season from 2003 to 2008. Stools were collected from people and dogs inhabiting the Amami Islands, i.e., Kikai, Amami, Kakeroma, Uke, Yoro and Okinoerabu, Japan. It was confirmed that the infective ratio of Strongyloides was 2.8% of 660 residents studied and 10.0% of their 55 dogs. The owners who had parasite-carrier dogs were not found to have parasites, and, conversely the dogs who were kept by owners having parasites were free of parasites. The epidemiological results of the present study demonstrate that natural infection of Strongyloides does not occur between humans and dogs.