context: intestinal parasites induce detectable histopathological changes, which have been studied in groups with known diagnosis of parasitic disease. there is no available study with a larger base without previous diagnosis. objective: to describe clinical and histopathological findings of parasitosis diagnosed by endoscopic biopsy in patients submitted to upper digestive endoscopy. methods: recorded biopsies archive at "complexo hospitalar professor edgar santos" , a general teaching hospital in the state of bahia, northeast brazil, from january 1995 to january 2009, were reviewed. one thousand ten duodenal biopsy reports were found. reports positive for parasites had their specimens reviewed and photographed. all blocks of biopsy selected as case were retrieved and reviewed by an experienced pathologist. clinical, laboratorial and endoscopic data were collected. results: eleven biopsies showed parasites, including cases of cryptosporidium sp. and strongyloides stercoralis. vomiting (91%), abdominal pain (78%), diarrhea (78%) and weight loss (78%) were usual symptoms. seventy-five percent had duodenal mucosa changes on endoscopy, while 25% have no changes. anemia and low serum albumin were important laboratorial data. hiv infection association was observed. villus atrophy and reactive epithelium were usual in strongyloides cases. conclusions: no endoscopic or histopathologic finding was pathognomonic. one percent of duodenal endoscopic biopsies showed parasites.