We worked with 185 middle-class patients above 18 years of age, both sexes, who presented diarrhea and/or chronic gastrointestinal disorders. The faeces were collected serially in formol 10% and processed in the following way: direct microscopy, with and without wet staining, concentration by Ritchie's method, 1% safranine technique for a specific investigation of Cryptosporidium sp., and faecal sieving macroparasites. Twenty eight point six of the studied patients showed at least one enteroparasite in their faeces, 48 harboured one parasite and 5 harboured two parasites. The following parasites were found and their corresponding percentages in the entire studied population are given below: Blastocystis hominis 15.7%, Giardia lamblia 7.5%, Cryptosporidium sp. 1.6%, Entamoeba coli 3.3%, Chilomastix mesnilii 1.1%, Ancylostoma duodenale-Necator americanus 0.5%, Ascaris lumbricoides 0.5%, Enterobious vermicularis 0.5% y Endolimax nana 0.5%. The most frequently found enteroparasites in the positive patients were B. hominis and G. lamblia. Cryptosporidium sp. was diagnosed in only three patients. The source of infection could be presumed in all of them. The symptomatology coincided with that described for this coccid in the bibliography. In spite of the fact that they were HIV seronegative patients the diarrhea was not self-limiting, but the immunologic profile of their relatives remained unknown and no other cause of immunosuppression could be detected with justified chronicity. The treatment with spiramycin was effective. Giardiasis was found in 17 patients, and the source of infection could not be inferred in any of them. They all had chronic diarrhea and their most frequent symptoms were abdominal pain, metallic taste, flatulency and nausea. Most of these patients were harboured one parasite, and only 2 of them simultaneously presented another faecal parasite associated to G. lamblia. Treatment with metronidazole was successful in all of them. Twenty nine patients were found to have B. hominis. The source of infection could not be inferred, this amoeboid was present as the only parasite in 25 patients. Predominant symptoms were flatulence, abdominal distention and colis. All patients suffered from chronic diarrhea, alternating, in some cases, with constipation. Good therapeutic results were obtained with metronidazole. Considering that one third of the patients examined presented faecal parasites associated to chronic disorders, it is important to insist on the detection of parasites to chronic disorders, it is important to insist on the detection of parasites using appropriate diagnostic techniques since the application of specific therapy made their eradication possible as well as relieving the patients' symptomatology.