In order to determine the epidemiological factors and clinical symptoms associated with Strongyloides stercoralis infection, we carried out a descriptive study with a control group in the District of Chanchamayo, Province of Chanchamayo, Junin, Peru. Group I (n = 50) represented those individuals with strongyloidosis and group II (n = 50) were those who tested negative for S. stercoralis by parasitological methods. Epidemiological variables significantly associated with group I were: bathing in the river 3-4 times per week, consuming non-drinking water, defecating in the field; and with group II: drinking boiled water, wearing sneakers and living in houses with cement floor. The clinical symptoms of epigastric pain, daily abdominal pain, semi liquid feces, liquid feces, daily defecation frequency, urticaria and nausea were significantly associated with group 1; whereas more solid feces and defecating every other day were significantly associated with group II. Among individuals under the age of 20 there was a higher percentage of malnutrition according to the weight-age index in group I (p = 0.045). We conclude that infection by S. stercoralis should be suspected in persons from tropical areas who are in frequent contact with rivers or streams or live close to watercourses, who have gastroenterological or dermatological symptoms or who are malnourished, especially if they are children or adolescents.